Post on 03-Jan-2016
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