Pierre Burdet, Z.Saghi, A.N.Filippin, A.Borrás, P.A.Midgley

Ultramicroscopy, 160 (2016) 118–129

DOI: 10.1016/j.ultramic.2015.09.012

This paper presents a novel 3D method to correct for absorption in energy dispersive X-ray (EDX) mi- croanalysis 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 com- positions 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.