The PEAC Institute of Multiscale Sciences, Chengdu, Sichuan 610031, People's Republic of China.
Institute of Applied Physics and Computational Mathematics, Beijing 100094, People's Republic of China.
J Synchrotron Radiat. 2019 Sep 1;26(Pt 5):1412-1421. doi: 10.1107/S160057751900732X. Epub 2019 Aug 1.
High-brightness coherent ultrashort X-ray free-electron lasers (XFELs) are promising in resolving nanoscale structures at the highest temporal resolution (∼10 fs). The feasibility is explored of resolving ultrafast fragmentation of liquids at the nanoscale with single-shot small-angle X-ray scattering (SAXS) on the basis of large-scale molecular dynamics simulations. Fragmentation of liquid sheets under adiabatic expansion is investigated. From the simulated SAXS patterns, particle-volume size distributions are obtained with the regularization method and average particle sizes with the weighted Guinier method, at different expansion rates. The particle sizes obtained from simulated SAXS are in excellent agreement with direct cluster analysis. Pulse-width effects on SAXS measurements are examined. The results demonstrate the feasibility of resolving the nanoscale dynamics of fragmentation and similar processes with SAXS, and provide guidance for future XFEL experiments and data interpretation.
高亮度相干超短 X 射线自由电子激光（XFEL）在以最高时间分辨率（约 10fs）解析纳米级结构方面具有很大的潜力。本研究基于大规模分子动力学模拟，探索了利用单次小角 X 射线散射（SAXS）解析纳米尺度液体超快碎裂的可行性。研究了在绝热膨胀下液体薄片的碎裂。通过正则化方法从模拟的 SAXS 图谱中获得了粒子体积尺寸分布，并通过加权古尔尼埃法获得了不同膨胀率下的平均粒子尺寸。从模拟的 SAXS 中获得的粒子尺寸与直接的团簇分析结果非常吻合。还研究了脉冲宽度对 SAXS 测量的影响。结果表明，利用 SAXS 解析碎裂和类似过程的纳米级动力学是可行的，为未来的 XFEL 实验和数据解释提供了指导。
