Basics in steady state and time resolved...

55
Basics in steady state and time resolved spectroscopy Dr. Christian Litwinski

Transcript of Basics in steady state and time resolved...

Page 1: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Basics in steady state and time resolved spectroscopy

Dr Christian Litwinski

Group Prof Nyokong

Synthesis of Phthalocyanines and NanoparticlesSensorsElectrochemistry

Photodynamic TherapyNonlinear Optical Materials

3

Contentbull Steady state absorption spectroscopy

Absorbance purity extinction coefficient ε aggregation

bull Steady state fluorescence spectroscopyFluorescence Investigation of FRET

bull Time correlated single photon counting (TCSPC)Lifetime of first excited state Investigation of FRET

bull Laser flash photolysis

Population and lifetime of triplet state

bull Singlet oxygen luminescence detectionSinglet oxygen quantum yield

bull X-ray diffraction spectroscopyStructure and size of samples

bull X-ray photoelectron spectroscopy

elemental composition chemical state and electronic state of the elements in a material

4

Electromagnetic radiation

light

identification

origin

radio waves

sun

nuclear

magnetic

resonance

electronsmol

rot

mol

vibr

outer

atomic

shell

inner

atomic

shell

atomic

core

beta-

tronsynchrotron

cosmic

radiation

spin change NMRESR

spectroscopy

Rotation and

vibration

IR

spectroscopy

Valence electron

transitions

UVVIS

spectroscopy

Core electron

transition crystal

structure

X-ray spectroscopy

3 D Crystal

structure

X-ray

tomography

Elemental

particles

Accelerator

Jabłoński Diagram

5

S0

S2

S1

T1

T2-1

5s)

Flu

ore

scen

ce(1

0-9s

10 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

Ph

osp

ho

resc

ence

(10

-6s

10 0s)

T-T Absorption

T3

S0

S2

S1

T1

T2A

bso

rpti

on

(10

-15

(10-9

s1

0 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

S0

S2

S1

T1

T2-

(10-9

s1

0 -8

s)

Inte

rnal

Co

nv

ersi

on

(10

-12s

10 -1

1s)

Intersystemcrossing

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

Ab

sorp

tio

n

T3

N

NH

N

HN

N

NH

N

HN

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

NN

N

N N

N

N N

PorphinPhthalocyanin

Naphthalocyanin

Tetrabenzo-Porphyrin

Tetraaza-Porphyrin

Tetrapyrazino-tetraazaporphyrin

N

H N

NH

N

NN

HN

N

N

Anthracocyanin

Phthalocyanine

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 2: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Group Prof Nyokong

Synthesis of Phthalocyanines and NanoparticlesSensorsElectrochemistry

Photodynamic TherapyNonlinear Optical Materials

3

Contentbull Steady state absorption spectroscopy

Absorbance purity extinction coefficient ε aggregation

bull Steady state fluorescence spectroscopyFluorescence Investigation of FRET

bull Time correlated single photon counting (TCSPC)Lifetime of first excited state Investigation of FRET

bull Laser flash photolysis

Population and lifetime of triplet state

bull Singlet oxygen luminescence detectionSinglet oxygen quantum yield

bull X-ray diffraction spectroscopyStructure and size of samples

bull X-ray photoelectron spectroscopy

elemental composition chemical state and electronic state of the elements in a material

4

Electromagnetic radiation

light

identification

origin

radio waves

sun

nuclear

magnetic

resonance

electronsmol

rot

mol

vibr

outer

atomic

shell

inner

atomic

shell

atomic

core

beta-

tronsynchrotron

cosmic

radiation

spin change NMRESR

spectroscopy

Rotation and

vibration

IR

spectroscopy

Valence electron

transitions

UVVIS

spectroscopy

Core electron

transition crystal

structure

X-ray spectroscopy

3 D Crystal

structure

X-ray

tomography

Elemental

particles

Accelerator

Jabłoński Diagram

5

S0

S2

S1

T1

T2-1

5s)

Flu

ore

scen

ce(1

0-9s

10 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

Ph

osp

ho

resc

ence

(10

-6s

10 0s)

T-T Absorption

T3

S0

S2

S1

T1

T2A

bso

rpti

on

(10

-15

(10-9

s1

0 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

S0

S2

S1

T1

T2-

(10-9

s1

0 -8

s)

Inte

rnal

Co

nv

ersi

on

(10

-12s

10 -1

1s)

Intersystemcrossing

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

Ab

sorp

tio

n

T3

N

NH

N

HN

N

NH

N

HN

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

NN

N

N N

N

N N

PorphinPhthalocyanin

Naphthalocyanin

Tetrabenzo-Porphyrin

Tetraaza-Porphyrin

Tetrapyrazino-tetraazaporphyrin

N

H N

NH

N

NN

HN

N

N

Anthracocyanin

Phthalocyanine

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 3: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

3

Contentbull Steady state absorption spectroscopy

Absorbance purity extinction coefficient ε aggregation

bull Steady state fluorescence spectroscopyFluorescence Investigation of FRET

bull Time correlated single photon counting (TCSPC)Lifetime of first excited state Investigation of FRET

bull Laser flash photolysis

Population and lifetime of triplet state

bull Singlet oxygen luminescence detectionSinglet oxygen quantum yield

bull X-ray diffraction spectroscopyStructure and size of samples

bull X-ray photoelectron spectroscopy

elemental composition chemical state and electronic state of the elements in a material

4

Electromagnetic radiation

light

identification

origin

radio waves

sun

nuclear

magnetic

resonance

electronsmol

rot

mol

vibr

outer

atomic

shell

inner

atomic

shell

atomic

core

beta-

tronsynchrotron

cosmic

radiation

spin change NMRESR

spectroscopy

Rotation and

vibration

IR

spectroscopy

Valence electron

transitions

UVVIS

spectroscopy

Core electron

transition crystal

structure

X-ray spectroscopy

3 D Crystal

structure

X-ray

tomography

Elemental

particles

Accelerator

Jabłoński Diagram

5

S0

S2

S1

T1

T2-1

5s)

Flu

ore

scen

ce(1

0-9s

10 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

Ph

osp

ho

resc

ence

(10

-6s

10 0s)

T-T Absorption

T3

S0

S2

S1

T1

T2A

bso

rpti

on

(10

-15

(10-9

s1

0 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

S0

S2

S1

T1

T2-

(10-9

s1

0 -8

s)

Inte

rnal

Co

nv

ersi

on

(10

-12s

10 -1

1s)

Intersystemcrossing

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

Ab

sorp

tio

n

T3

N

NH

N

HN

N

NH

N

HN

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

NN

N

N N

N

N N

PorphinPhthalocyanin

Naphthalocyanin

Tetrabenzo-Porphyrin

Tetraaza-Porphyrin

Tetrapyrazino-tetraazaporphyrin

N

H N

NH

N

NN

HN

N

N

Anthracocyanin

Phthalocyanine

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 4: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

4

Electromagnetic radiation

light

identification

origin

radio waves

sun

nuclear

magnetic

resonance

electronsmol

rot

mol

vibr

outer

atomic

shell

inner

atomic

shell

atomic

core

beta-

tronsynchrotron

cosmic

radiation

spin change NMRESR

spectroscopy

Rotation and

vibration

IR

spectroscopy

Valence electron

transitions

UVVIS

spectroscopy

Core electron

transition crystal

structure

X-ray spectroscopy

3 D Crystal

structure

X-ray

tomography

Elemental

particles

Accelerator

Jabłoński Diagram

5

S0

S2

S1

T1

T2-1

5s)

Flu

ore

scen

ce(1

0-9s

10 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

Ph

osp

ho

resc

ence

(10

-6s

10 0s)

T-T Absorption

T3

S0

S2

S1

T1

T2A

bso

rpti

on

(10

-15

(10-9

s1

0 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

S0

S2

S1

T1

T2-

(10-9

s1

0 -8

s)

Inte

rnal

Co

nv

ersi

on

(10

-12s

10 -1

1s)

Intersystemcrossing

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

Ab

sorp

tio

n

T3

N

NH

N

HN

N

NH

N

HN

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

NN

N

N N

N

N N

PorphinPhthalocyanin

Naphthalocyanin

Tetrabenzo-Porphyrin

Tetraaza-Porphyrin

Tetrapyrazino-tetraazaporphyrin

N

H N

NH

N

NN

HN

N

N

Anthracocyanin

Phthalocyanine

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 5: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Jabłoński Diagram

5

S0

S2

S1

T1

T2-1

5s)

Flu

ore

scen

ce(1

0-9s

10 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

Ph

osp

ho

resc

ence

(10

-6s

10 0s)

T-T Absorption

T3

S0

S2

S1

T1

T2A

bso

rpti

on

(10

-15

(10-9

s1

0 -8

s)

(10

-12s

10 -1

1s)

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

S0

S2

S1

T1

T2-

(10-9

s1

0 -8

s)

Inte

rnal

Co

nv

ersi

on

(10

-12s

10 -1

1s)

Intersystemcrossing

10 -8s

10 -6s10 0s

(10

-6s

10 0s)

Ab

sorp

tio

n

T3

N

NH

N

HN

N

NH

N

HN

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

NN

N

N N

N

N N

PorphinPhthalocyanin

Naphthalocyanin

Tetrabenzo-Porphyrin

Tetraaza-Porphyrin

Tetrapyrazino-tetraazaporphyrin

N

H N

NH

N

NN

HN

N

N

Anthracocyanin

Phthalocyanine

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 6: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

N

NH

N

HN

N

NH

N

HN

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

N

NH

N

NN

HN

N

N

NN

N

N N

N

N N

PorphinPhthalocyanin

Naphthalocyanin

Tetrabenzo-Porphyrin

Tetraaza-Porphyrin

Tetrapyrazino-tetraazaporphyrin

N

H N

NH

N

NN

HN

N

N

Anthracocyanin

Phthalocyanine

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 7: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

7

Steady State Absorption

Absorption spectrumAbsorption spectrum shows the fraction of incident light absorbed by the

material over a range of frequencies

Lamp

Mirror

MCMirrorMirror Mirror

Mirror

Detector

Sample

Reference

Amplifier

Aperture

Computer

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 8: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

ε = molar extinction coefficient [ε] =M-1cm-1

c = concentration [c] = mol

σ = absorption cross section of one mol [σ] = cm2

s = pathway [s] = cm

n = number of mol

Lambert-Beer-Law

8

picture by University of Bremen

I(s)= I0-IA

I = I0 10(-εcs) or I = I0 e(-σns)

OD

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 9: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Determinaton of ε

I = I0 10(-εcs)

0000002 0000004 0000006 0000008 0000010

01

02

03

04

05

06

07

08

ε (845nm) = 75491 M-1 cm

-1

OD

CS

DPCH2 in Toluene

OD= -εcs

N

NH

N

NN

HN

N

N

R R

R

R

R R

N

NH

N

NN

HN

N

NR

R

R R

R R

300 400 500 600 700 800 900

00

02

04

06

08

10

Ab

so

rption

[a

u]

Wellenlaumlnge [nm]

H2Pc-H

2Pc

ZnPc-ZnPc

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 10: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Origin of spectra in Pcs

e g

a 2 u

b 2 u

a 1 u

e g

b 1 u

b 2 u

x xx xx xx x

x x

a 2 u

B1

B2

Q

Ring Metallated Pc (D4h)

10

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 11: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Q

B

Metallated Pc (D4h)

11

Also N L and C bands at high

energy in transparent

solvents chloroform

dichloromethane

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 12: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

eg split -hence Q band split

N

NN

N

NN

N

N

H

H H2Pc

Unmetallated Pc complexes (D2h)

Metallated Pc (D4h)

eg

a1u

a2u

Q bands

12

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 13: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

H2Pc spectra ndash Not split in basic solvents (eg DMSO

pyridine)

DMSO

DMSO

13

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 14: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

H2Pc

H2Nc

H2Ac

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

N N

N

NN

N

N

N

H

H

The Q band splitting of H2Pcs becomes smaller at

longer wavelength

300 700 1000nm

14

Expansion of the π electron system

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 15: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Q

Q+

Q-

Monomer Dimer

1Eu(1)

1A1g

1Eu(1)

1Eg(1)

J aggregates ndash edge to edge red shifted ndash NOT COMMON

H aggregates ndash face to face blue shifted - COMMON

15

Aggregation

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 16: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

0

02

04

300 500 700

Ab

sorb

an

ce

Wavelength (nm)

monomeraggregate

-H

16

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 17: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Zn

N N

N

NN

N

N

NHOOC

HOOC

HOOC COOH

COOH

COOH

COOHHOOC

0

02

04

06

08

1

500 600 700 800

Ab

so

rba

nce

Wavelength (nm)

N

N

N

N

N

N

N

N

HOOC

COOHHOOC

Si ClCl

COOH

Plurality of ligands and aggregation

Not aggregated

17

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 18: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

N

N

N

N

N

N

N

NTi

O

R1

R1

R1

R1

R2

R2

R2

R2

Effects of solvents on aggregation

Durmas Ahsen Nyokong Dalton Trans (2007)1235

SCH(CH2O(CH

2CH

2O)

2C

2H

5)

2R2 =

Chloroform

18

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 19: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Proof of non-aggregation Beerrsquos law

19

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 20: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

0

02

04

06

08

1

12

14

350 450 550 650 750 850

Ab

sorb

ance

Wavelengthnm

Proof of aggregation dimer peaks

decreases faster than monomer on

dilution

20

Proof of non-aggregation Beerrsquos law

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 21: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Proof of aggregation Effects of

Surfactants

pH 74

300 400 500 600 700 800

Ab

sorb

an

ce

Wavelength (nm)

No surfactant

surfactant

21

(eg Cremophore EL )(eg Cremophore EL )

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 22: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

22

Steady State Fluorescence

Picture by Mizower

Fluorescence spectrumFluorescence spectrum is plot of fluorescence intensity vs registration

wavelength (frequency energy) at one excitation wavelength

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 23: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

23

Steady State Fluorescence

600 700 800

00

02

04

06

08

10

Ab

sorp

tion

[au

]

Wellenlنnge [nm]

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 24: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Fluorescence1 Stokes Law a maximum of fluorescence

spectrum is red-shifted compared to a

maximum of the corresponding absorption

spectrum (Reasons Franck-Condon rule)

2 Mirror Image Rule a fluorescence

spectrum (plotted in energy scale) strongly

resembles the mirror image of the

absorption spectrum (Reason the vibrational

energy level spacing is similar for the ground

and excited states)

3 Universal Relationship (betwenn Abs-Flu)

Wfl(ν) = C(T)sdotK(ν)Abssdotexp(-hνkT)

4 Kasha-Vavilov Rule the fluorescence

spectrum shows very little dependence on

the wavelength of the excitation (Reasons

the emission occurs exclusively from the lowest

singlet excited electronic state)

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 25: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Fluorescence

Low solvent polarity

∆E1

∆E0

En

erg

y

eqS0

neqS0

FCS1 neq

S1

FCS0

eqS1

aν 0

flν t

flν infinν fl

High solvent polarity

( ) R

t

flflfl

t

fl eτ

minusinfininfin sdotνminusν+ν=ν 0

Dependency of the spectral

position of a fluorescence

band on time

τR is solvent relaxation time

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 26: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Quantum Yield

bull yield of product relative to amount of photons

absorbed

bull sum off all quantum yields in a process is

26

absorbed photons ofnumber

molecules formedproduct ofnumber =Φ

Examples

ΦR = Quantum yield of reaction

Φfl = Fluorescence quantum yield

ΦPh = Phosphorescence quantum yield

ΦISC = Intersystem crossing quantum yield

ΦIC = Internal conversion quantum yield

Φ∆ = Singlet oxygen quantum yield

1le

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 27: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Fluorescence Quantum Yield Φf

bull absolute measurements spectrometer with

Integrating sphere (Ulbricht Sphere)

bull comparative measurements optical spectrometer

27

absorbed photons ofnumber

photons cefluorescen ofnumber =Φ fl

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 28: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

600 700 800 900 1000

0

2000

4000

6000

8000

10000

12000

inte

nsityλ

wavelength [nm]

SymPcH2

600 700 800

0

200

400

600

800

1000

1200

inte

nsity

wavelength [nm]

H2TPP

Example comparative

measurement

I=51575

Φf=011

I=330989

Φf=071

2

2

stdsamplestd

samplestdSample

stdsamplenODI

nODIΦ=Φ

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 29: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

perp

perp

+

minus=

II

IIP

||

||

Polarization

perp

perp

sdot+

minus=

II

IIr

2||

||

Anisotropy

r

rP

P

Pr

+=

minus=

2

3

3

2

5

1cos3

cos3

1cos3 2

02

2

0

minusθ=

θ+

minusθ= rP

Perrin expression

40202

1

3

100 leleminusleleminus rP

5

1cos3 2

0

minusβ= rrββββ

Polarizer

Analyzer

At ββββ = 547degdegdegdeg (Magic Angle)

r = 0

Lakowicz J Principles of fluorescence spectroscopy Plenum Press New York 1999

Polarization of Fluorescence

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 30: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

bull Dipole-dipole resonance interaction between photoexcited donor

molecule (D) and acceptor molecule (A) (in the most cases A is in the

ground state)

Energy of dipole-dipole interaction between donor and acceptor molecules

( ) ( )( )

minus= RR ADADddRR

M micromicromicromicromicromicromicromicromicromicromicromicromicromicromicromicro23

31

Foerster Resonace Energy Tranfer

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 31: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln900046

0

45

0

2

ν

ννεν

τπ

Φχsdot= int

dI

RNnk A

n

DD

a

Ddd

DA

( ) 1~~ =ννint dIn

D( )22 coscos3cos AD θθminusα=χ

bull Overlap of the fluorescence spectrum of D

and the absorption spectrum of A

bull High extinction coefficient of A molecule

bull Short distance between D and A molecules

bull Right orientation of transition dipole

moments (χχχχ2 nenenene 0)

bull High fluorescence quantum yield of D

High probability of EET if

Foerster Resonace Energy Tranfer

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 32: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

1

6

0

0

τ

=R

Rk

DDA

Rate of dipole-dipole EET

( ) ( ) ~

~~~

128

10ln9000445

0

26

ννεν

π

Φχsdot= int

dI

NnR A

n

D

a

D

If R = R0 then the fluorescence of the D is quenched by a factor 2

Foerster Resonace Energy Tranfer

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 33: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Factors influencing FRET Efficiency

Good spectral overlap

500 600 700 800

No

rma

lize

d In

ten

sit

y

Wavelength (nm)

Pc absQD ems

Pc flu

λλλελ partint= 4)()( PcQDfJ

DF

DAF

ssEffΦ

Φminus= 1

660

60

rR

REff

+=

JnRDFΦtimes= minus42236

0 1088 κ

Foumlrster radius

FRET efficiency

iiii ταΣτ =DF

DAF

trEffτ

τminus= 1

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 34: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

34

TCSPC

bull Determination of fluorescence lifetime

bullbull Time resolution 60 ps up to 1 Time resolution 60 ps up to 1 μμss

bullbull Measurements with low fluorescence quantum yield possible Measurements with low fluorescence quantum yield possible

(lt1)(lt1)

4 6 8 10 12 14 16 18 20

0

2000

4000

6000

8000

10000

Time [ns]

Co

un

ts

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 35: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

TCSPC Principle

rArr repeat the dwell time measurement many times ldquocount how many photons arrived after what timerdquoie build a histogram

rArr time axis is not continuous but divided into ldquotime binsrdquo

rArr Note not more than one photon per laser pulse can be registered

Photon emission is a stochastic process

Photon

1

laser

pulse

Photon

2

laser

pulse

eg 24 ns eg 45 ns

laser

pulse

no

photon

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 36: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

TCSPC principle

bull detection of single photons caused by a periodic light signal

bull light intensity is so low that probability to dectect one photon in one period is very low

bull thus periods with more than one photon are very rare

bull the time difference between laser pulse and every detected photon will be measured

bull with many pulses (millions) one gets a distribution of time differences which correspond to the fluorescence lifetime

bull time resolution up 20ps with a MCP-PMT and 150 ps with a PMT

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 37: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

15052008 Seminarvortrag Ch Litwinski 37

ldquoStartrdquo ldquoStop2rdquo

Laser

ldquoStop1rdquo

Luminescence

∆t

N

ldquoPile-uprdquo effect

TCSPC principle

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 38: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

38

TCSPC setup

Monochromator

Histogram

electronic

PCldquoStoprdquo

ldquoStartrdquo

Filter

Sample

(MCP)-PMT

Photo diode

Beam splitter

Laser

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 39: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

bull PMT pulses from photomultiplier

bull SYNC synchron pulses

bull CFD Constant-Fraction Discriminator

measures the exact time of detection

bull TAC Time-to-Amplitude Convertercondensator which loads up in the time between

SYNC signal and PMT signal

bull PGA Programmable Gain Amplifier

amplifies the TAC- output voltage with

tunable factor

bull ADC Analog-to-Digital-Converter

convert voltage to a number between 0

(fastest photons) and eg 4096 (latest)

bull MEM Memory

has in our case 4096 counter which will be

increased by 1 if a photon is detected in the

certain time period

TCSPC schematic diagram

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 40: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Data Analysis

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 41: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

Zaumlhlr

ate

Zeit [ns]

Rodamin 6G

Apparatefunktion

4 6 8

1

10

100

1000

10000 Apparatefunktion

Zeit [ns]

Zauml

hlra

te45 ps

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 42: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

)(exp)( ztIRFt

atpfi i

iminusotimes

= sum

τModel function

( )

2

2 )()(sum

minus=

N

i

ii

t

tdtpf

σχχ2-value

Data )(i

td

Data AnalysisData Analysis

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 43: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

2 4 6 8 10 12 14 16 18 20 22

0

2000

4000

6000

8000

10000

2 4 6 8 10 12 14 16 18 20 22

-6

-4

-2

0

2

4

6

Zaumlhlrate

Zeit [ns]

Messung

Fit

Re

sid

uie

n

Zeit [ns]

τ= 373plusmn001

Data AnalysisData Analysis

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 44: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

Example

N N

Zn

N N

N

N

N

NH

O

O

N

N N

Zn

N N

N

N

N

N

O O

O

S N

S OH

O

DCC48 hrt

QD

QD

0

50

100

150

200

250

300

350

400

500 550 600 650 700 750 800

Inte

ns

ity

(au

)

Wavelength (nm)

(a)

(b)

(c)

Compound Relative A1 ττττF-1 (ns)

(plusmnplusmnplusmnplusmn 05)

Relative A2 ττττF-2 (ns)

(plusmnplusmnplusmnplusmn 03)

CdTe MPA QD 057

(061a)

264

(263 a)

043

(039 a)

34

(43 a)

QD-ZnttbIPc-linked 021 96 079 17

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 45: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

45

Decay Associated Fluorescence

Spectroscopy (DAFS)bull Fluoresence lifetime of a homogenius species is independant from the

detection wavelength

bull Measurement of time resolved fluroescence at different detectionwavelengths

bull Data analysis at different detection wavelength is given by the model

bull Global fit over all data sets

Result Fluorescence spectra of differents species with

different fluorescence lifetimes

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 46: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

46

640 660 680 700 720 740 760 780 800

00

02

04

06

08

10

N

orm

In

tensitauml

t

Wellenlaumlnge [nm]

Fluoreszenz

DAFS

τfl

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 47: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

47

Data

=M

N

M

n

N

aa

a

aa

S

Κ

ΜΜ

Κ

1

11

1

)( ωλMatrix of amplitude

coefficients

Matrix of lifetimes

otimesminus

otimesminus

)()exp(

)()exp(

)(

1

1

N

N

l

l

nn

ttIRFt

ttIRFt

t

δτ

δτ

δτ Κ

N species

M Wavelength

L time channels

Nilanglang1

Mw langlang1

Ll langlang1

=M

L

M

l

L

II

I

II

D

1

11

1

ωω

Κ

Data AnalysisData Analysis

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 48: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

48

)()(~

nntSD δτλ Πsdot=Model matrix

22 )

~(

11ωωω

ω

σχρ

οDDLM

global minus= sumχ2-Value

Data AnalysisData Analysis

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 49: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

49

Example

M= H2 H2Pc

M= Zn ZnPc

O

CH3

CH3

R=

N

N

N

NN

N

N

N

R R

R

R

R R

M

R

R

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

M= H2 H2Pc-H2Pc

M= Zn ZnPc-ZnPc

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 50: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

50

650 700 750 800 850 900 950 1000

00

02

04

06

08

10

N

orm

F

luore

szen

z

Wellenlaumlnge [nm]

Fluoreszenz

ZnPc ZnPc-ZnPc RTZn LTZn

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

N

N

N

NN

N

N

N

M M M

N

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

N

N

N

NN

N

N

N

R

R

R R

R

R

M M

MN

N

N

NN

N

N

N

R R

R

R

R R

M

R

RN

N

N

NN

N

N

N

R R

R

R

R R

N

N

N

NN

N

N

NR

R

R R

R R

M M

ExampleExample

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 51: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

51

750 nm 790 nm

800 820 840 860 880 90000

02

04

06

08

10

12

14

16

740 nm

In

ten

sitauml

t [a

u]

Wellenlaumlnge [nm]

ZnPc-ZnPc

Anregung bei

ExampleExampleFluoreszenz

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 52: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

52

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

000

001

002

003

004

005

006

DAFS

A

mp

litud

e [au

]

Wellenlaumlnge [nm]

ExampleExample

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 53: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

53

ZnPc-ZnPc

τfl = 076 plusmn 002 ns

800 820 840 860 880 900

00

02

04

06

08

10 DAFS

Fluoreszenz

No

rm In

ten

sitaumlt

Wellenlaumlnge [nm]

ExampleExample

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 54: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

54

882 nm

860 nm

800 820 840 860 880 900 920

00

02

04

06

08

10

836 nm

N

orm

In

ten

sitauml

t

Wellenlaumlnge [nm]

Anregung bei

H2Pc-H2Pc

ExampleExampleFluoreszenz

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS

Page 55: Basics in steady state and time resolved spectroscopyacademic.sun.ac.za/physics/websites/alc_workshop... · Lakowicz, J. Principles of fluorescence spectroscopy; Plenum Press: New

55

800 810 820 830 840 850 860 870 880 890 900 910

0000

0025

0050

τ1 = 043 plusmn 002ns

τ2 = 081 plusmn 002ns

τ3 = 087 plusmn 002 ns

A

mplit

ude

[a

u]

Wellenlaumlnge [nm]

H2Pc-H2Pc

ExampleExampleDAFS