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

时间分辨X射线散射将被用来研究短脉冲激光诱导无序化后材料的类液态结构和动力学。特别是，我们想回答无序状态的结构如何取决于激发强度，无序路径和材料类型，以及结构如何随时间演变的问题。飞秒激光脉冲将辐照薄的固体薄膜材料。在激光诱导的无序化之后，在正入射透射几何中观察到了LCLS自由电子激光的延时硬X射线脉冲的散射。测量的漫散射图案作为泵探测时间延迟的函数产生的结构因子的瞬态变化，从该对相关函数将被导出。拟议的实验利用了最初几皮秒期间受激样品的惯性约束，并将提供有关电子激发、温度和压力极端条件下材料无序状态结构特性的信息。

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.