Lasers at the Interface of Chemistry and PhysicsChemistry and Physics (Biology? Engineering?)

Cather SimpsonD t t f Ph iDepartment of Physics

School of Chemical Sciences

c.simpson@auckland.ac.nzp @

photonfactory.auckland.ac.nz

The Photon FactoryUsing short and ultrashort laser

pulses ...

to probe chemistry physics...to probe chemistry, physics

... to machine on the μ to nanoscale

Important events happens on ultrashort time scales

Laser Interactions with Matter

35 fs pulses100 fs pulses

10 ns pulses

"Research-grade" femtosecond system⇒ 800 nm (tunable)⇒ 100 fs (or 35 fs or ps scale)

Laser Micro‐ and Nanomachining

⇒ 100 fs (or 35 fs, or ps-scale)⇒ up to 3.5 mJ/pulse (λ dependent)⇒ 6 μm feature size⇒ 100 nm limit (Ag on glass λ/8)⇒ 100 nm limit (Ag on glass λ/8)

"Standard" nanosecond system⇒ 248 nm; ~10 ns

t 10 J/ l⇒ up to 10 mJ/pulse⇒ 2 μm feature size⇒ 300 nm limit feature size

Enabling TechnologyBasic, Targeted‐Basic and Applied Research

Engender Technologies, Ltd.

500 μm

1-3 μm

The Photon Factory James Tour & coworkers

P=P photochemistry – a new twist on an old taletwist on an old tale

The Photon Factory ‐ Enabling Technology• robust, reliable source of pulsed laser light• pulses from nano‐ to femtoseconds• wavelengths from ultraviolet to infraredg f f• low to high pulse energies

New photoactive electronic materials

Prof. John Protasiewicz

Transparent P t ti FilProtective Film

Dr. John Payton

Light Emitting Polymer Film

Protective FilmDr. Huo‐Lei Peng

Dr. Brian AlberdingDr. Nicole  Dickson

Expanding the toolbox

phospha-PPVsphospha-PPVs …polymer OLEDsphotoactive polymers (photonics)solar energy harvesting?solar energy harvesting?

Prof. John Protasiewicz

PAn

PPV

P

n

PPE

n

PPV n

PP

PPEn

P

n

Photochemistry and the periodic table

“… it is rather the heavyelements which behave

ll d t thnormally and not themore familiar elementsof the first row”

-- W. Kutzelnigg (1984) Angew. Chem. Int. Ed. Engl. 23:272-295

Photochemistry and Photophysics of Diphosphenes

PP

Mes

M

PP

But

But

ButBut

PP MesMes

MesProf. John Protasiewicz

Prof. Masaaki YoshifujiPP Bu

But

But

j

Dmp = 2,6-Mes2C6H3

Mes* = 2,4,6-tri-t-butylphenyl Yoshifuji, M. et al. (1981) JACS 103:4587.

Urzenius E., Protasiewicz,J.D. (1996) Main Group Chem. 1:369.

What excited states are involved?What pathways between states are important?

Photochemistry and Photophysics of Diphosphenes

What pathways between states are important?What structural features influence photobehaviour?

PP

Inversion

PP

PP2P

P

Dissociative

2

PP

P PRR

P PRotation

P PR'R'

What excited states are involved?What pathways between states are important?

Photochemistry and Photophysics of Diphosphenes

Quantum chemistry calculations

What pathways between states are important?What structural features influence photobehaviour?

PP

Inversion

Density functional theoryCASPT2//CASSCF

PP

PP2P

P

Dissociative

2

Ultrafast Spectroscopy ??P

PP P

RR

P P

Ultrafast Spectroscopyfs-Transient Absorption

impact ofligands

??Rotation

P PR'R'

- ligands- excitation λ- solvent fs-Time resolved Raman

Ultrafast Transient Absorption & CASPT2//CASSCF

Ultrafast Transient Absorption & CASPT2//CASSCF

π– π∗

rban

ce

ε ∼ 5 − 12,000400 nm excitationS2

Abs

or n+ – π∗ε ∼ 300 − 1500ππ* (S2) singlet state

τrise = 130 fsτ = 275 fs250 300 350 400 450 500

Wavelength (nm)

480 nm e citation

τ1 = 275 fsτ2 = 20 ps

Mes

480 nm excitationS1

PP MesMes

Mes

n+π* (T1) triplet stateτrise = 230 fs

τ1 = 16 ps

DmpP=PDmpτ2 = 200 ps

Ultrafast Transient Absorption & CASPT2//CASSCF

The Photon FactoryUsing short and ultrashort laser

pulses ...

to probe chemistry physics...to probe chemistry, physics

... to machine on the μ to nanoscale

Current Photon Factory GroupDr. Chuck Rohde (Physics)S h Th (Ch i t PhD t d t)Sarah Thompson (Chemistry – PhD student)Julie Kho (Chemistry – PhD student)Christiaan Hougaard (BSc Hons Physics)Simon Ashforth (BTech Physics) Past MembersS o s o ( ec ys cs)Sean Liew (BTech Physics)Edward Woon Wei An (BTech Physics)Jessica Hendy (BA Hons Anthropology)J P k (BS H Ch i t )

Laura Harvey (MSc Physics graduate)Kaidi Liang (BTech Physics)Ling Yan Pang (BTech Physics)Amy Lin (MSc Physics)James Park (BSc Hons Chemistry)

Josh Bradfield (Mechatronics Engineering)Fraser MacMillan (Engineering Science)Peter Hosking (Mechatronics Engineering)

Amy Lin (MSc. Physics)Emma Simpson (Physics exchange)Hafizah Rahim

Current Collaborators

Center for Chemical Dynamics

g ( g g)Mona Xin Zhu (Biomedical Engineering)Hayley Ware (Mechanical Engineering)Matthew Edmond (Engineering Science)Isaac Hamling (Engineering Science)

Current CollaboratorsProf. David WilliamsDr. Bryon WrightDr Charles UnsworthIsaac Hamling (Engineering Science)

Geran Zhang (Biomedical Engineering)

Dr. Charles UnsworthProf. Larry ChamleyProf. John ProtasiewiczProf. Terry Gustafson

Vice Chancellor’s Strategic Development FundVice Chancellor s Strategic Development Fund

Vice Chancellor's MIRE Program

Faculty of Science

School of Chemical Science & Department of Physics

Auckland UniServices

National Science Foundation (USA) NationalNational Science Foundation (USA), National Institutes of Health (USA), Department of Education (USA)