Measuring Ultrafast Dynamics with High Harmonic Generation Sources

and X-ray Free Electron Lasers

Alvaro Sanchez GonzalezProf. Jon Marangos

Prof. Jim Clarke

Ultrafast Science

Muybridge (1872)2 ms mechanical shutter

• Ultrafast “gates”

• Ultrafast light sources– Pump-probe technique

τ

time

Ultrafast Science

• Few-femtosecond/attosecond regime– Electron dynamics– Fast electron initiated nuclear dynamics

• Interesting in all processes initiated by sudden ionization– Light harvesting– Chemistry: photosynthesis, isomerization,…

• Understand and then control the processes

Summary

• HHG and attosecond transient absorption– Setup and commissioning of our beamline– Some first results– Upgrades

• X-ray free electron lasers: Hole dynamics in glycine at LCLS– Idea of the experiment– Mode of operation of the FEL

and diagnostics

Our beamline

• Ti:Shapp: 800 nm (8 mJ) • OPA signal: ~1400 nm (1.7 mJ) • HHG: <~100 eV (XUV-SXR ~107 photons/pulse)• 30 fs pulses, 1 kHz• All in vacuum

Pump-probe preparation

• Mach-Zhender interferometer

• Intensity, polarization and ellipticity control

• 120 as accuracy

Interaction and measurement

• Interaction region• Flat field spectrometer

– MCP+Phosphor Screen

Attosecond transient absorption in He

• XUV-Pump/IR probe

XUV initiated HHG?

Upgrades

• Multiple targets: gas, liquid and solids

• High collection efficiency electron magnetic bottle

• Full rep-rate data recording

• Attosecond pulses (< 1 fs long) and energies up to 300 eV

Glycine experiment at LCLS

• Measure hole dynamics

10A’

1h

2h 1pInner-valence

C - 1s

Ionization Threshold

Pump270 eV

Quantum superposition of states

|ψ>= e-tΔE/ћ |φ1> + |φ2>

|φ1> = a1|1h> + a2|2h1p>

|φ2> = b1|1h> + b2|2h1p>

Glycine experiment at LCLS

• Measure Measure hole dynamics

Inner-valence

C - 1s

Ionization Threshold

Probe

275 eV

Auger

electron

signature

Only possible for pure 1h states

10A’

1h

2h 1p

Mode of operation

• Two bunch mode: – Low charge: < 4 fs pulses– Two colour

time

Bunch 1

Bunch 2

time

Slot 1

Slot 2τ

Elec

tron

cur

rent

X-ra

y po

wer

After undulator

Signal channels

• Transverse cavity:

• Optical X-ray spectrometer• High acceptance electron ToF

x-ray spectrometer• High resolution electron

magnetic bottle

Femtosecond x-ray pulse temporal characterization in free-electron lasers using a transverse deector - Ding et al.

Example no lasing trace (Run 160)

Time axis (pixels)

Ene

rgy

axis

(pi

xels

)

580 590 600 610 620 630

300

400

500

600

700

800

Example lasing trace (Run 161)

Time axis (pixels)

Ene

rgy

axis

(pi

xels

)

500 520 540 560

300

400

500

600

700

800

Example no lasing trace (Run 153)

Time axis (pixels)

Energ

y a

xis

(pix

els

)

570 580 590 600 610 620 630350

400

450

500

550

600

650

700

Example lasing trace (Run 151)

Time axis (pixels)

Energ

y a

xis

(pix

els

)

540 550 560 570 580 590

350

400

450

500

550

600

650

700

750

-100 -50 0 50 100 150 2000

1

2

3

4

5

6

7x 10

21 Electron current

Curr

ent

[#ele

ctr

ons/s

])

Time (fs)

No lasing B1

Lasing B1No lasing B2

Lasing B2

-100 -50 0 50 100 150 200-5

0

5

10Center of mass energy

Time (fs)

Centr

al energ

y w

ith r

espect

to C

OM

(pix

els

)

-100 -50 0 50 100 150 2000

1

2

3

4

5

6

7

8Energy RMS

Time (fs)

Energ

y R

MS

CO

M (

pix

els

)

-100 -50 0 50 100 150 200-0.5

0

0.5

1

1.5

2

2.5Best reconstruction (84.8% agreement)

Time (fs)

Pow

er

(GW

)

COM method B1

RMS method B1COM method B2

RMS method B2

Conclusion

• It is a great time to work in ultrafast science– Optimization of HHG techniques– Novel techniques for XFELs– Interesting for physics,

chemistry, material science,…

Measuring Ultrafast Dynamics with High Harmonic Generation Sources

and X-ray Free Electron Lasers

Alvaro Sanchez GonzalezProf. Jon Marangos

Prof. Jim Clarke