The present work explores electron diffraction methods for studying the structure of metallic clusters stabilized with thiol groups, which are susceptible to structural damage caused by electron beam irradiation. There is a compromise between the electron dose used and the size of the clusters since they have small interaction volume with electrons and as a consequence weak reflections in the diffraction patterns. The common approach of recording individual clusters using nanobeam diffraction has the problem of an increased current density. Dosage can be reduced with the use of a smaller condenser aperture and a higher condenser lens excitation, but even with those set ups collection times tend to be high. For that reason, the methods reported herein collects in a faster way diffraction patterns through the scanning across the clusters under nanobeam diffraction mode. In this way, we are able to collect a map of diffraction patterns, in areas with dispersed clusters, with short exposure times (milliseconds) using a high sensitive CMOS camera. When these maps are compared with their theoretical counterparts, oscillations of the clusters can be observed. The stability of the patterns acquired demonstrates that our methods provide a systematic and precise way to unveil the structure of atomic clusters without extensive detrimental damage of their crystallinity.

中文翻译：

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通过电子衍射方法减少受保护金簇的结构损伤。

本工作探索电子衍射方法，以研究用硫醇基稳定的金属团簇的结构，该团簇易受电子束辐照引起的结构破坏。在使用的电子剂量和簇的尺寸之间存在折衷，因为它们与电子的相互作用体积小，结果是衍射图谱中的反射较弱。使用纳米束衍射记录单个簇的常用方法存在电流密度增加的问题。使用较小的聚光镜孔径和较高的聚光镜激发可以减少剂量，但即使采用这些聚光镜，收集时间也往往很高。是因为，本文所报道的方法通过在纳米束衍射模式下对簇的扫描而以更快的方式收集了衍射图样。通过这种方式，我们能够使用高灵敏度的CMOS摄像头在较短的曝光时间（毫秒）内，在具有分散簇的区域中收集衍射图谱。当将这些图与理论对应图进行比较时，可以观察到团簇的振荡。所获得图案的稳定性表明，我们的方法提供了一种系统且精确的方法来揭示原子团簇的结构，而不会对其结晶度造成广泛的损害。将这些图与其理论对应图进行比较时，可以观察到团簇的振荡。所获得图案的稳定性表明，我们的方法提供了一种系统且精确的方法来揭示原子团簇的结构，而不会对其结晶度造成广泛的损害。将这些图与其理论对应图进行比较时，可以观察到团簇的振荡。所获得图案的稳定性表明，我们的方法提供了一种系统且精确的方法来揭示原子团簇的结构，而不会对其结晶度造成广泛的损害。