标题： 原位单次衍射通量映射用于X射线自由电子激光脉冲 显示英文标题

标题： In-situ single-shot diffractive fluence mapping for X-ray free-electron laser pulses

摘要： 自由电子激光器（FEL）在极紫外（XUV）和X射线区域为在高功率密度下进行实验提供了可能性，特别是允许利用通量依赖的吸收和散射实验来揭示在越来越短波长下的非线性光-物质相互作用。 在XUV和X射线区域发现此类非线性效应引起了极大的兴趣，但由于光子强度的固有逐束波动以及聚焦FEL光束的通常结构化、非高斯的空间强度分布，这些效应难以理解和建模。 目前，聚焦光束斑点是与实际实验分开表征和优化的。 在这里，我们首次同时测量了固体样品的衍射信号以及实际样品上的相应单束空间通量分布。 这种新的原位表征方案实现了快速直接的监控，从而控制样品照明，这对于定量理解X射线和XUV FEL实验中的非线性光-物质相互作用是必要的。 显示英文摘要

摘要： Free-electron lasers (FEL) in the extreme ultraviolet (XUV) and X-ray regime opened up the possibility for experiments at high power densities, in particular allowing for fluence-dependent absorption and scattering experiments to reveal non-linear light-matter interactions at ever shorter wavelengths. Findings of such non-linear effects in the XUV and X-ray regime are met with tremendous interest, but prove difficult to understand and model due to the inherent shot-to-shot fluctuations in photon intensity and the often structured, non-Gaussian spatial intensity profile of a focused FEL beam. Presently, the focused beam spot is characterized and optimized separately from the actual experiment. Here, we present the first simultaneous measurement of diffraction signals from solid samples in tandem with the corresponding single-shot spatial fluence distribution on the actual sample. This new in-situ characterization scheme enables fast and direct monitoring and thus control of the sample illumination which ultimately is necessary for a quantitative understanding of non-linear light-matter interaction in X-ray and XUV FEL experiments.