Three-dimensional measurement of elemental distribution in minute samples by combination of in-air micro-PIXE and STIM

Abstract

A technique of measuring three-dimensional (3D) distribution of trace elements in a minute sample was studied using the in-air micro-PIXE (Particle Induced X-ray Emission) system. A 3D distribution was acquired by means of reconstructing numbers of projection images of the sample obtained by micro-PIXE analyses from different directions. This is basically the same technique as X-ray CT (Computed Tomography). However, when this technique was applied to the in-air micro-PIXE analysis, the X-ray yields should be corrected in taking account of such parameters as the X-ray production cross section, the X-ray attenuation coefficient, the energy of an incident particle, and the 3D densities of major elements in the analysis sample. In this study, STIM (Scanning Transmission Ion Microscopy)-CT was used to obtain the 3D density map of the sample. Corrected 3D distributions of sulfur and iron in a minute test sample were successfully measured with this technique in combination of STIM-CT and in-air micro-PIXE.