Slater Thomas J A, Janssen Arne, Camargo Pedro H C, Burke M Grace, Zaluzec Nestor J, Haigh Sarah J
School of Materials, University of Manchester, Manchester M13 9PL, UK.
Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
Ultramicroscopy. 2016 Mar;162:61-73. doi: 10.1016/j.ultramic.2015.10.007. Epub 2015 Oct 22.
This paper presents an investigation of the limitations and optimisation of energy dispersive X-ray (EDX) tomography within the scanning transmission electron microscope, focussing on application of the technique to characterising the 3D elemental distribution of bimetallic AgAu nanoparticles. The detector collection efficiency when using a standard tomography holder is characterised using a tomographic data set from a single nanoparticle and compared to a standard low background double tilt holder. Optical depth profiling is used to investigate the angles and origin of detector shadowing as a function of specimen field of view. A novel time-varied acquisition scheme is described to compensate for variations in the intensity of spectrum images at each sample tilt. Finally, the ability of EDX spectrum images to satisfy the projection requirement for nanoparticle samples is discussed, with consideration of the effect of absorption and shadowing variations.
本文介绍了对扫描透射电子显微镜中能量色散X射线（EDX）断层扫描的局限性及优化的研究，重点关注该技术在表征双金属AgAu纳米颗粒的三维元素分布方面的应用。使用来自单个纳米颗粒的断层数据集对使用标准断层扫描支架时的探测器收集效率进行了表征，并与标准低背景双倾支架进行了比较。利用光学深度剖析来研究探测器阴影的角度和起源与样品视场的关系。描述了一种新颖的时变采集方案，以补偿每个样品倾斜角度下光谱图像强度的变化。最后，讨论了EDX光谱图像满足纳米颗粒样品投影要求的能力，并考虑了吸收和阴影变化的影响。
