Evaluation of Corrections for X-Ray Microanalysis in the ESEM

Abstract

A number of methods have been proposed to correct for the electron beam scattering effects on xray microanalysis in the environmental scanning electron microscope (ESEM). This paper presents an evaluation of two of these methods. The Doehne method is based on the observation that x-ray counts due to the unscattered electron beam increase with decreasing chamber pressure whereas the inverse is true for x-ray counts due to scattered electrons. The x-ray count intercept, at zero pressure, of the regression lines relating x-ray counts to chamber vapor pressure is an estimate of the high-vacuum intensity. The Gauvin method is based on the relationship between x-ray counts and the fraction of the electron beam that is unscattered, fp.The fraction of the unscattered beam is calculated using an equation derived from scattering theory and uses the accelerating voltage, the gas path length, and the chamber vapor pressure.