Time-resolved crystallography with X-ray free-electron lasers enables structural characterization of light-induced reactions on ultrafast timescales. To be biologically and chemically relevant, such studies must be carried out in an appropriate photoexcitation regime to avoid multiphoton artifacts, a common issue in recent studies. We describe numerical and experimental approaches to determine how many photons are needed for single-photon excitation in microcrystals, taking into account losses by scattering.

中文翻译：

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飞秒串行晶体学超快泵浦探针实验的照明指南。

X射线自由电子激光器的时间分辨晶体学能够在超快的时间尺度上对光诱导的反应进行结构表征。为了在生物学和化学上相关，必须在适当的光激发机制下进行此类研究，以避免多光子伪影，这是最近研究中的常见问题。我们描述了数值和实验方法来确定微晶中单光子激发需要多少个光子，同时考虑了散射造成的损失。