The field of time-resolved macromolecular crystallography has been expanding rapidly after free electron lasers for hard x rays (XFELs) became available. Techniques to collect and process data from XFELs spread to synchrotron light sources. Although time-scales and data collection modalities can differ substantially between these types of light sources, the analysis of the resulting x-ray data proceeds essentially along the same pathway. At the base of a successful time-resolved experiment is a difference electron density (DED) map that contains chemically meaningful signal. If such a difference map cannot be obtained, the experiment has failed. Here, a practical approach is presented to calculate DED maps and use them to determine structural models.

中文翻译：

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时间分辨 X 射线数据分析的实际注意事项

自硬 X 射线自由电子激光器 (XFEL) 面世后，时间分辨高分子晶体学领域迅速扩展。从 XFEL 收集和处理数据的技术扩展到同步加速器光源。尽管这些类型的光源之间的时间尺度和数据收集方式可能有很大不同，但对所得 X 射线数据的分析基本上沿着相同的路径进行。成功的时间分辨实验的基础是包含具有化学意义的信号的差异电子密度 (DED) 图。如果无法获得这样的差异图，则实验失败。在这里，提出了一种计算 DED 地图并使用它们来确定结构模型的实用方法。