The R Factor: The X-Ray Loss Due to Electron Backscatter

Abstract

With the evolution of electron microprobes that employ more stable electronics which permit high precision measurements of x-ray intensity, a new interest has arisen in the accuracy of methods and parameters used to compute the matrix corrections for quantitative electron probe microanalysis. One of the two components that contribute to the “atomic number correction,” part of the ZAF matrix correction procedure, is the R-factor. The R-factor is an estimate of the ratio of the total inner shell ionization which is actually produced in the specimen over that which would occur in the absence of electron backscattering. There are several formulations of the R-factor in use today. They are based on either empirical fits to experimental data on electron backscattering and backscattered electron energy distributions [1] or on data generated by a Monte Carlo simulation for electron scattering in solids [2]. In this publication we will examine several of these formulations and compare the results obtained by each method.