Application of Monte Carlo Calculations to Improve Quantitative Electron Probe Microanalysis

The generation of x rays from solid samples under electron bombardment is the basis of electron probe microanalysis (EPMA), a widely used technique for materials analysis. The problem of quantitative analysis, i.e. the transformation of the measured x-ray intensities into element concentrations, is generally solved by means of approximate, semi-empirical algorithms. These algorithms provide reliable results for samples that are homogeneous at the micron scale, and, with suitable modifications, they can also be used for thin films. However, when the sample volume from which x-rays are generated is not homogeneous (e.g. small particles, multilayer films, lamellae structures...) or under unconventional measurement conditions (e.g. low voltage, low overvoltage, oblique incidence, standardless analysis...) the legitimacy of the simplifications underlying conventional quantification algorithms is not firmly established and there is a need for more realistic procedures. This need has lead to the use of the Monte Carlo simulation (MC) method.