Many nanoparticles in fields such as heterogeneous catalysis undergo surface structural fluctuations during chemical reactions, which may control functionality. These dynamic structural changes may be ideally investigated with time-resolved in situ electron microscopy. We have explored approaches for extracting quantitative information from large time-resolved image data sets with a low signal to noise recorded with a direct electron detector on an aberration-corrected transmission electron microscope. We focus on quantitatively characterizing beam-induced dynamic structural rearrangements taking place on the surface of CeO2 (ceria). A 2D Gaussian fitting procedure is employed to determine the position and occupancy of each atomic column in the nanoparticle with a temporal resolution of 2.5 ms and a spatial precision of 0.25 Å. Local rapid lattice expansions/contractions and atomic migration were revealed to occur on the (100) surface, whereas (111) surfaces were relatively stable throughout the experiment. The application of this methodology to other materials will provide new insights into the behavior of nanoparticle surface reconstructions that were previously inaccessible using other methods, which will have important consequences for the understanding of dynamic structure–property relationships.

中文翻译：

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用原位透射电子显微镜探索纳米粒子时空表面动力学的方法

多相催化等领域中的许多纳米颗粒在化学反应过程中会发生表面结构波动，这可能会控制功能。这些动态结构变化可以通过时间分辨来理想地研究原位电子显微镜。我们已经探索了从大型时间分辨图像数据集中提取定量信息的方法，该数据集具有低信噪比，使用像差校正透射电子显微镜上的直接电子检测器记录。我们专注于定量表征发生在 CeO 表面上的光束诱导的动态结构重排2（二氧化铈）。采用二维高斯拟合程序来确定纳米颗粒中每个原子柱的位置和占有率，时间分辨率为 2.5 ms，空间精度为 0.25 Å。发现局部快速晶格膨胀/收缩和原子迁移发生在（100）表面上，而（111）表面在整个实验过程中相对稳定。将该方法应用于其他材料将为纳米粒子表面重建的行为提供新的见解，这些行为以前使用其他方法无法获得，这将对理解动态结构-性能关系产生重要影响。