What Do We Need to Look Out for When Doing Energy Dispersive Xray Analysis in the Environmental Scanning Electron Microscope?

Abstract

The environmental scanning electron microscope (ESEM) is not typically used for quantitative analysis by energy dispersive x-ray spectrometry (EDS) because the electron beam is scattered by the chamber gas forming a broad tail or skirt rather than a focused spot. Scattered electrons can contribute x-rays from areas not directly under the beam, which compromises the spectrum for quantitative analysis. For specimens compatible with high vacuum, quantitative EDS analysis in a conventional electron microscope is preferred. However, the ESEM has found its niche in providing a vehicle for investigating those specimens that for any of a variety of reasons are not suitable for high vacuum electron microscopy and microanalysis. For these specimens, it is important that we find the most accurate way to perform EDS analysis in the low vacuum environment.Research has focused on reducing, accounting for, predicting, or measuring the electron scattering on a simplified system. Instrumental tricks to reduce the scattering of the primary electron beam have been reported in the past.