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

大気マイクロPIXEとSTIMを用いた微小試料中の元素分布の三次元測定

佐藤 隆博; 及川 将一*; 神谷 富裕

Sato, Takahiro; Oikawa, Masakazu*; Kamiya, Tomihiro

本研究は、微小試料中の元素分布を三次元的に測定することを目的としており、試料に対し複数の方向から二次元のマイクロPIXE分析を行い、X線CTの技術を応用して画像再構成を行うことで三次元測定を実現した。このような手法で三次元測定を行う場合、X線の検出量をX線の発生断面積,減弱係数,試料の密度に基いて、測定データを補正することが必要である。このため、あらかじめSTIM-CTを用いて測定した試料中の密度分布を考慮して画像再構成を行い、その結果、試料中に含まれる硫黄と鉄の分布を三次元で測定することに成功した。

This study aims to measure three-dimensional distribution of trace elements in a minute sample. Such a distribution was acquired by reconstruction of projection images in much the same way as X-ray CT using many two-dimensional images of micro-PIXE taken from various directions. When the image reconstruction technique is applied to in-air micro-PIXE analysis, the X-ray yields must be corrected using X-ray production cross sections, X-ray attenuation coefficients, energies of incident particles, and three-dimensional density of major elements in the analysis target. In this study, STIM-CT was used to measure the density map of the target. The in-air micro-PIXE images of sulfur and iron in a minute target were corrected using coefficients calculated from the three-dimensional density map. Thus the three-dimensional distribution of sulfur and iron in the target was successfully measured by the combination of STIM-CT and in-air micro-PIXE.