We present a comprehensive investigation of a recently introduced method to determine transient structures of molecules in excited electronic states with sub-ångstrom resolution from time-resolved gas-phase scattering signals. The method, which is examined using time-resolved X-ray scattering data measured on the molecule N-methylmorpholine (NMM) at the Linac Coherent Light Source (LCLS), compares the experimentally measured scattering patterns against the simulated patterns corresponding to a large pool of molecular structures to determine the full set of structural parameters. In addition, we examine the influence of vibrational state distributions and find the effect negligible within the current experimental detection limits, despite that the molecules have a comparatively high internal vibrational energy. The excited state structures determined using three structure pools generated using three different computational methods are in good agreement, demonstrating that the procedure is largely independent of the computational chemistry method employed as long as the pool is sufficiently expansive in the vicinity of the sought structure and dense enough to yield good matches to the experimental patterns.

中文翻译：

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从时间分辨气相X射线散射确定激发态分子结构

我们目前对最近引入的一种方法进行全面研究，该方法可从时间分辨的气相散射信号中确定具有亚微米分辨率的激发电子态中的分子的瞬态结构。该方法使用在分子N上测量的时间分辨X射线散射数据进行检验直线加速器相干光源（LCLS）上的-methylmorpholine（NMM）将实验测得的散射图与对应于大量分子结构的模拟图进行比较，以确定整套结构参数。此外，尽管分子具有相对较高的内部振动能，但我们检查了振动状态分布的影响，并发现在当前的实验检测极限内其影响可忽略不计。由使用三种不同计算方法生成的三个结构池确定的激发态结构非常吻合，