Validating Electron Pair Distribution Function Analysis: The Role of Multiple Scattering, Beam, Measurement, and Processing Parameters

Electron pair distribution function (ePDF), combined with four-dimensional scanning transmission electron microscopy (4D-STEM), provides a powerful approach for uncovering detailed information about the local atomic structure and structural variations in disordered materials. However, achieving high accuracy in ePDF analysis requires careful control of experimental and instrumental parameters. In this study, we systematically investigate the effects of key electron optical and measurement parameters on ePDF analysis using simulations as the primary tool, complemented by experimental validation. Specifically, we examine the influence of diffraction angle range, beam convergence semi-angle, detector pixel resolution, sample thickness (multiple scattering effect), noise, and electron beam precession on the resulting ePDF. By integrating multi-slice electron diffraction simulations with experimental diffraction data, we identify optimal conditions for accurate ePDF extraction and provide practical guidelines to improve analysis precision and reliability. These insights contribute to refining ePDF techniques, particularly for applications involving amorphous and nanostructured materials.

电子对分布函数（Electron pair distribution function, ePDF）与四维扫描透射电子显微镜（four-dimensional scanning transmission electron microscopy, 4D-STEM）相结合，为揭示无序材料的局域原子结构与结构变化细节提供了强有力的研究方法。然而，要实现高精度的ePDF分析，需对实验与仪器参数进行精细化调控。本研究以模拟为主要研究工具，辅以实验验证，系统探究了关键电子光学与测量参数对ePDF分析的影响。具体而言，本研究考察了衍射角范围、电子束会聚半角、探测器像素分辨率、样品厚度（多重散射效应）、噪声以及电子束预进对最终ePDF结果的影响。通过将多层切片电子衍射模拟与实验衍射数据相结合，本研究确定了精准提取ePDF的最优实验条件，并给出了提升分析精度与可靠性的实用指南。上述研究成果有助于完善ePDF技术体系，尤其适用于非晶与纳米结构材料的相关应用场景。