An evaluation of absorption correction functions for electron probe microanalysis

Abstract

The absorption correction function necessary to quantitative electron probe microanalysis has been studied experimentally by a number of authors. The experimental data of these groups are systematically reviewed here to determine their dependence on primary electron accelerating potential E ₀, excitation potential ratio U and atomic number Z. The data are compared by assuming that the mean depth of x-ray production IMG1 characterizes the distribution of x-ray emission with depth Φ(ρz) accurately enough to show the influence of E ₀, U and Z on the absorption correction function. Monte Carlo calculations are used to show that IMG1 can be described by a modified approximation to the Bethe electron retardation law. The experimental data are then compared, using this modified approximation to take account of the influence of E ₀, U and Z. On this basis there is good agreement among the various data that do not have large errors. This agreement suggests the possibility of a correction function based on the method of comparison used. The proposed correction function is compared to a well-accepted correction model over large ranges of E ₀, U and Z.