Transient structure of laser-generated disordered states investigated by ultrafast diffuse X-ray scattering

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Time-resolved diffuse X-ray scattering will be used to investigate the structure and dynamics of liquid-like states of materials after short-pulse laser-induced disordering. In particular, we would like to answer the question how the structure of the disordered state depends on the excitation strength, the disordering pathway and the type of material, and how the structure evolves over time. Thin foils of solid materials will be irradiated by femtosecond optical laser pulses. Subsequent to the laser-induced disordering the scattering of a timedelayed hard X-ray pulse from the LCLS free electron laser will be observed in normalincidence transmission geometry. Measurements of the diffuse scattering pattern as a function of the pump-probe time delay yield the transient changes of the structure factor from which the pair-correlation function will be derived. The proposed experiments are taking advantage of the inertial confinement of the excited samples during the first few picoseconds and will provide information on the structural properties of disordered states of materials under extreme conditions of electronic excitation, temperature and pressure.