[Salamanca Seminar] Laser-driven hard x-ray sources for femtosecond Bragg diffraction experiments

durch Thomas Elsaesser (Max Born Institute)

Montag 22.02.2021, 14:00 → 16:00 Europe/Berlin

Femtosecond structural dynamics at atomic length and time scales has been studied by a variety of x-ray methods. Time-resolved Bragg diffraction from crystalline samples gives. insight in coupled nuclear and electronic motions and allows for deriving spatially resolved electron density maps in nonequilibrium states. Experiments with both accelerator-based and. laser-driven hard x-ray sources have addressed the spatio-temporal dynamics underlying coupled elementary excitations, chemical reactions, and phase transitions. Laser-driven table-top sources of femtosecond hard x-ray pulses hold strong potential for such
studies at a laboratory frame. X-ray pulses synchronized to optical pulses with a negligible timing jitter have been generated at kilohertz repetition rates and been applied in a broad range of optical pump / x-ray probe experiments. This talk gives an introduction in this technology and discusses the underlying physical processes. A recently demonstrated x-ray source driven by mid-infrared pulses will be presented as the most advanced implementation. of such concepts. This source provides femtosecond 8 keV pulses at a 1 kHz repetition rate. with an unprecedented flux of up to 1.5×10^12 x-ray photons per second.

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