1. Alvaro Sanchez Gonzalez Prof. Jon Marangos Prof. Jim Clarke
Measuring Ultrafast Dynamics with High Harmonic Generation Sources and X-ray Free Electron Lasers
Alvaro Sanchez Gonzalez
Prof. Jon Marangos
Prof. Jim Clarke

2. Ultrafast Science Ultrafast “gates” Ultrafast light sources
Pump-probe technique
Muybridge (1872)
2 ms mechanical shutter τ
time
In 1872 railroad magnate Leland Stanford wagered $25,000 that a galloping horse, at some point in stride, lifts all four hooves off the ground. To prove it, Stanford employed English photographer Eadweard Muybridge. After many attempts, Muybridge developed a camera shutter that opened and closed for only two thousandths of a second, enabling him to capture on film a horse flying through air (see movie on the left; note that temporal resolution of a stationary image on the right is not sufficient to resolve the details of the motion).

3. 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
-valence – inner valence electron interactions

4. 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

5. 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

6. Pump-probe preparation
Mach-Zhender interferometer
Intensity, polarization and ellipticity control
120 as accuracy

7. Interaction and measurement
Interaction region
Flat field spectrometer
MCP+Phosphor Screen

8. Attosecond transient absorption in He
XUV-Pump/IR probe
Schematic of the main mechanisms proposed to explain the oscillation
of the photoabsorption probability in the case of APT (a) and SAP excitation
(b)–(c). (a) Interference between two parts of a transiently bound EWP excited
by subsequent pulses in the APT [2, 5]. (b) Resonant absorption lines of the 1snp
series affected by sub-cycle ac Stark shift and light-induced structures associated
with two-photon/two-color processes [6, 7]. IR dressed states are represented
with wavy lines. (c) ‘Which way’ interference between direct extreme-ultraviolet
(XUV) excitation and an IR-assisted two-color transition [8–10].
XUV initiated HHG?

9. 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

10. Glycine experiment at LCLS
Measure hole dynamics
Inner-valence
C - 1s
Ionization
Threshold
Pump
270 eV
10A’ 1h
2h 1p
Coherent evolution of the state
|ψ>= e-tΔE/ћ |φ1> + |φ2>
|φ1> = a1|1h> + a2|2h1p>
|φ2> = b1|1h> + b2|2h1p>
Quantum superposition of states

11. Glycine experiment at LCLS
Measure Measure hole dynamics
Auger electron
signature
Inner-valence
C - 1s
Ionization
Threshold
Probe
275 eV
10A’ 1h
2h 1p
Coherent evolution of the state
Only possible for pure 1h states

12. Mode of operation Two bunch mode: Low charge: < 4 fs pulses
Two colour
After undulator
Slot 1
Bunch 1
Electron current
X-ray power τ
Slot 2
Bunch 2
time
time

13. 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.

14. 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,…
The talk was not really that long to have too much to sumarize, but I think the main conclussion is that…
These two tools complement each other

15. Alvaro Sanchez Gonzalez Prof. Jon Marangos Prof. Jim Clarke
Measuring Ultrafast Dynamics with High Harmonic Generation Sources and X-ray Free Electron Lasers
Alvaro Sanchez Gonzalez
Prof. Jon Marangos
Prof. Jim Clarke