High-energy electrons induce sample damage and motion at the nanoscale to fundamentally limit determination of molecular structures by electron diffraction. Using fast event-based electron counting (EBEC) detectors, we characterize electron beam-induced crystal lattice reorientations (BIR) that appear to broadly affect molecular microcrystals. These lattice reorientations are sufficiently large to bring reflections entirely in or out of excitation, occur as early events in the decay of diffracted signal due to radiolytic damage, and coincide with beam-induced migrations of crystal bend contours within the same fluence regime and at the same illuminated location on a crystal. These effects are observed in crystals of biotin, a series of amino acid metal chelates, and a six-residue peptide, suggesting that incident electrons inevitably warp molecular lattices. The precise orientation changes experienced by a given microcrystal are unpredictable, but are measurable by indexing individual diffraction patterns during beam-induced decay. Often, reorientations can tilt a crystal lattice several degrees away from its initial position, and for an especially beam-sensitive Zn(II)-methionine chelate, are associated with dramatic crystal quakes prior to 1 e-/Å2 exposure. As BIR is coincident with the early stages of beam-induced damage, it echoes the beam-induced motion observed in single particle cryoEM. As with motion correction for cryoEM imaging experiments, correction of BIR-induced errors during data processing could improve the accuracy of MicroED data.

中文翻译：

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绘制分子纳米晶体中电子束诱导的晶格重新取向

高能电子在纳米尺度上引起样品损伤和运动，从根本上限制了电子衍射对分子结构的测定。使用基于事件的快速电子计数 (EBEC) 探测器，我们表征了电子束诱导的晶格重新取向 (BIR)，这种取向似乎广泛影响分子微晶体。这些晶格重新取向足够大，足以将反射完全带入或带出激发，作为由于辐射分解损伤引起的衍射信号衰减的早期事件而发生，并且与在相同注量范围内和在水晶上相同的照明位置。这些效应在生物素晶体、一系列氨基酸金属螯合物和六残基肽中观察到，表明入射电子不可避免地会扭曲分子晶格。给定微晶体所经历的精确取向变化是不可预测的，但可以通过在光束诱导衰减期间索引各个衍射图案来测量。通常，重新取向会使晶格从其初始位置倾斜几度，对于光束敏感的 Zn(II)-蛋氨酸螯合物来说，在 1 e-/Å2 曝光之前与剧烈的晶体震动有关。由于 BIR 与束诱导损伤的早期阶段一致，因此它与单粒子冷冻电镜中观察到的束诱导运动相呼应。与冷冻电镜成像实验的运动校正一样，数据处理过程中 BIR 引起的误差的校正可以提高 MicroED 数据的准确性。