Burdet Pierre, Saghi Z, Filippin A N, Borrás A, Midgley P A
Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS, Cambridgeshire, UK.
Department of Materials Science and Metallurgy, University of Cambridge, Charles Babbage Road 27, Cambridge CB3 0FS, Cambridgeshire, UK.
Ultramicroscopy. 2016 Jan;160:118-129. doi: 10.1016/j.ultramic.2015.09.012. Epub 2015 Oct 3.
This paper presents a novel 3D method to correct for absorption in energy dispersive X-ray (EDX) microanalysis of heterogeneous samples of unknown structure and composition. By using STEM-based tomography coupled with EDX, an initial 3D reconstruction is used to extract the location of generated X-rays as well as the X-ray path through the sample to the surface. The absorption correction needed to retrieve the generated X-ray intensity is then calculated voxel-by-voxel estimating the different compositions encountered by the X-ray. The method is applied to a core/shell nanowire containing carbon and oxygen, two elements generating highly absorbed low energy X-rays. Absorption is shown to cause major reconstruction artefacts, in the form of an incomplete recovery of the oxide and an erroneous presence of carbon in the shell. By applying the correction method, these artefacts are greatly reduced. The accuracy of the method is assessed using reference X-ray lines with low absorption.
本文提出了一种新颖的三维方法，用于校正未知结构和成分的异质样品在能量色散X射线（EDX）微分析中的吸收。通过使用基于扫描透射电子显微镜（STEM）的断层扫描技术结合EDX，利用初始三维重建来提取所产生X射线的位置以及X射线穿过样品到达表面的路径。然后，通过逐体素估计X射线遇到的不同成分，计算出恢复所产生X射线强度所需的吸收校正值。该方法应用于包含碳和氧的核壳纳米线，这两种元素会产生被高度吸收的低能X射线。结果表明，吸收会导致主要的重建伪像，表现为氧化物的不完全恢复以及壳层中碳的错误存在形式。通过应用校正方法，这些伪像大大减少。使用低吸收的参考X射线线评估了该方法的准确性。
