Monte Carlo simulation code for confocal 3D micro-beam X-ray fluorescence analysis of stratifiedmaterials

Stratified materials are of great importance for many branches of modern industry, e. g. electronics or optics and for biomedical applications. Examination of chemical composition of individual layers and determination of their thickness helps to get information on their properties and function. A confocal 3D micro X-ray fluorescence (3D mu XRF) spectroscopy is an analytical method giving the possibility to investigate 3D distribution of chemical elements in a sample with spatial resolution in the micrometer regime in a non-destructive way. Thin foils of Ti, Cu and Au, a bulk sample of Cu and a three-layered sandwich sample, made of two thin Fe/Ni alloy foils, separated by polypropylene, were used as test samples. A Monte Carlo (MC) simulation code for the determination of elemental concentrations and thickness of individual layers in stratified materials with the use of confocal 3D mu XRF spectroscopy was developed. The X-ray intensity profiles versus the depth below surface, obtained from 3D mu XRF experiments, MC simulation and an analytical approach were compared. Correlation coefficients between experimental versus simulated, and experimental versus analytical model X-ray profiles were calculated. The correlation coefficients were comparable for both methods and exceeded 99%. The experimental X-ray intensity profiles were deconvoluted with iterative MC simulation and by using analytical expression. The MC method produced slightly more accurate elemental concentrations and thickness of successive layers as compared to the results of the analytical approach. This MC code is a robust tool for simulation of scanning confocal 3D mu XRF experiments on stratified materials and for quantitative interpretation of experimental results. Copyright (C) 2011 John Wiley & Sons, Ltd.