Specific effects and deconvolution in submicrometre EPMA: application to binary diffusion

Abstract

Electron probe (x‐ray) microanalysis (EPMA) is nowadays a classical and well‐established method for qualitative and (semi)quantitative evaluation of the elemental composition of the (near) surface of a sample on the micrometre scale. This technique can be used to determine concentration profiles due to (inter)diffusion in materials at submicrometre resolution if physical and geometrical effects that occur during the measurement process are accounted for. Standard phenomena are usually corrected by commercial software for a homogeneous elemental composition in the analysed area. However, in the case of a diffusion process on a small scale, the composition is no longer homogeneous and the effect of the hemispherical volume of the x‐ray emission on the spatial resolution of the concentration profiles, and consequently on the diffusion coefficients, has to be considered. A radial x‐ray distribution associated with the classical depth distribution, ϕ(z), allows for the definition of a 2D x‐ray emission function for medium to heavy materials. This enables one to study the effect of some geometrical parameters on the measured concentration profile and to propose a method of reconstructing the real weight fraction profile from the measured profile of the x‐ray intensities by using regularized deconvolution algorithms. Copyright © 2003 John Wiley & Sons, Ltd.

Quantification of Nano-inclusions by EPMA Using Conventional Accelerating Voltages

“…For more than four decades, the electron probe microanalysis (EPMA) has been routinely used to determine the chemical composition of materials on a micrometer scale. For analysis, typical operating conditions use beam energies in a range of 15-20 keV, which give spatial resolutions of about 2-4 µm for a material of mass density of 5 g/cm 3 . The volume of interaction can be reducing by decreasing the beam energy, but the large increase in spot size with tungsten gun EPMA at low beam energy limits the lateral resolution to a minimum of about 0.8 µm at 7 keV.…”

“…This approach requires firstly that the X-ray intensities coming from the inclusion and the matrix can be calculated and secondly that the surrounding material can be accurately determined. X-ray intensities can be calculated using Monte Carlo simulation [2] or specific analytical program [3]. In this work, to quantify the inclusions, an analytical X-ray distribution in three dimensions was developed.…”