Time-resolved pump-probe experiments at the LCLS

Abstract

Abstract:The first time-resolved x-ray/optical pump-probe experiments at the SLAC Linac Coherent Light Source (LCLS) used a combination of feedback methods and post-analysis binning techniques to synchronize an ultrafast optical laser to the linac-based x-ray laser. Transient molecular nitrogen alignment revival features were resolved in time-dependent x-rayinduced fragmentation spectra. These alignment features were used to find the temporal overlap of the pump and probe pulses. The strong-field dissociation of x-ray generated quasi-bound molecular dications was used to establish the residual timing jitter. This analysis shows that the relative arrival time of the Ti:Sapphire laser and the x-ray pulses had a distribution with a standard deviation of approximately 120 fs. The largest contribution to the jitter noise spectrum was the locking of the laser oscillator to the reference RF of the accelerator, which suggests that simple technical improvements could reduce the jitter to better than 50 fs. ©2010 Optical Society of America

Ultrafast Photovoltaic Response in Ferroelectric Nanolayers

“…We observed no evidence of x-ray-induced sample modification. The time resolution of this measurement is limited by timing jitter between laser and x-ray pulses, estimated to be 100 fs RMS [29]. The PTO (003) Bragg reflection was collected with either a point detector or an area detector as a function of laser delay and x-ray incidence angle (θ), probing the out-ofplane lattice parameter, c, inside the thin film.…”

XFEL experiments: jitter of pump–probe time delays and pulse intensities

“…X-ray techniques, in particularly XFEL techniques have proven to be extremely efficient, but a number of difficulties still limit, for the time being, their intrinsic power: the shot-to shot dispersion of pump-probe time delays and of pulse intensities. An important efforts has been made to solve this problem experimentally [2] [3] [4][5] [6] [7][8] [9]. The recent measure and sort technique [10] merits attention in this context.…”

Two-dimensional stimulated resonance Raman spectroscopy of molecules with broadband x-ray pulses

“…The x-ray interaction involves single particle, field driven, transitions between core and valence electronic orbitals and the manybody valence response to a transiently created core-hole. 30 Extensive theoretical 31 and experimental 32 work was applied toward using this unique source as a probe in time-dependent experiments. The low cross-section of the x-ray matter interaction make IR and optical pump/x-ray probe experiments more accessible than the all-x-ray pump-probe technique.…”

“…[33][34][35][36] Time-resolved optical pump/x-ray probe experiments 37 have been performed at the LCLS which highlight the experimental difficulties in synchronizing pump and probe pulses. 32 All-x-ray stimulated Raman experiments in which the pump and probe pulses both have x-ray frequencies are a natural extension of these techniques. Frequency-domain resonant inelastic x-ray scattering (RIXS) is a well established technique that probes the singleparticle occupied and unoccupied density of states around the resonant core by measuring the energy-resolved x-ray radiation spontaneously emitted by a core-excited state.…”