A further developed Monte Carlo model for the quantitative EPMA of complex samples

Abstract

In its conventional application the electron probe microanalysis (EPMA) is a suitable technique for the quantitative microanalysis of samples, which are homogeneous inside the excited volume. Depending on the beam energy and the target composition the measured x-ray intensities are emerging from depths between about 50 nm and some microns. They contain an integral information about the composition of the excited volume. Nevertheless, the sensitivity of this technique also allows the detection of thin films on substrates with thicknesses even less than one monolayer. For such samples composed inhomogeneously near the surface, e.g. thin layers on substrates or sandwich structures, detailed quantitative informations can only be obtained when the integral information can be deconvoluted properly from the intensities. A necessary prerequisite to solve this problem is the exact knowledge of the depth distribution of the generated x-ray intensities ϕ(ρz) in samples which are inhomogeneous inside the excited volume. Up to now ϕ(ρz) is rather unknown for such samples.

Electron Probe Microanalysis of Ni Silicides Using Ni-L X-Ray Lines

“…Obviously, a MAC obtained in this way is useful only for evaluating concentrations using XPP as a matrix correction method. For comparison purposes, k-ratios were also calculated using the Monte Carlo simulation programs PENEPMA (Llovet et al, 2005) and MONACO (Ammann and Karduck, 1990), developed at the Universities of Barcelona and Aachen, respectively. PENEPMA is based on the generalpurpose Monte Carlo code PENELOPE (Salvat, 2015).…”

Nondestructive Angle-resolved X-ray Depth Profiling: Interpretation of Angle-resolved Profiles Using a Monte Carlo Approach

“…It would be relatively straightforward to extend the software to interpret energy-resolved data, where the primary beam energy is varied to provide depth-sampling variation (Ammann and Karduck, 1990). It should also be possible to interpret the results from combining the techniques of energy-resolved and angle-resolved depth profiling in a single experiment, for example, to interpret signals collected for a number of geometric arrangements using multiple primary beam energies.…”

A Model for Characteristic X-Ray Emission in Electron Probe Microanalysis Based on the (Filtered) Spherical Harmonic () Method for Electron Transport

“…On the other hand, due to the strong assumptions on the material (homogeneous or varying only in depth), these models essentially limit the spatial resolution of EPMA to pixels that exceed the size of the interaction volume V , G where characteristic X-rays are generated due to ionization of atoms by high-energy beam electrons. k-ratios for materials with structures that deceed the interaction volume are typically computed by Monte Carlo (MC) simulation of a large number of electron trajectories (Ammann & Karduck, 1990;Joy, 1991;Ritchie, 2005;Gauvin et al, 2006;Salvat, 2015). While MC simulations can exhibit high physical accuracy, they are not well-suited to solve the inverse problem as they are computationally expensive and suffer from statistical noise, which makes the application of gradient-based minimization techniques difficult.…”