Recent developments of x-ray free electron lasers and pulsed electron sources have enabled ultrafast scattering to become an increasingly powerful tool for exploring molecular dynamics. This article describes our recent experimental and methodological advances in ultrafast gas-phase x-ray scattering experiments at the LCLS. A re-designed short-pathlength windowless diffractometer is coupled with careful optimization of sample density and independent normalization of x-ray intensity fluctuations to provide gas-phase scattering patterns with exceptionally high signal-to-noise ratios. These advances, coupled with careful geometry optimization and data treatment, provide both ground- and excited-state signals in excellent agreement with high level ab initio total scattering patterns.

X射线自由电子激光器和脉冲电子源的最新发展使超快散射成为探索分子动力学的强大工具。本文介绍了我们在LCLS上超快气相x射线散射实验中的最新实验和方法学进展。重新设计的短光程无窗衍射仪与仔细的样品密度优化和X射线强度波动的独立归一化相结合，可提供具有极高信噪比的气相散射图。这些进步，加上精心的几何优化和数据处理，可提供基态信号和激发态信号，并且与高水平的从头算起的总散射图非常吻合。