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

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).

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

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 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?

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 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

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

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

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.

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

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