Effects of Charging on Quantitative X-Ray Microanalysis Procedures in Environmental / Variable Pressure SEM

Abstract In variable pressure (VPSEM) and environmental SEM (ESEM) caution is required in the intepretation of x-ray data from non-conductive and electrically isolated samples for unique reasons. This paper reviews the documented procedures and presents data on hither-to undefined aspects. The most widely recognised artefacts are associated with the scatter of primary electrons from their convergent trajectory to the sample surface through interactions with the chamber gas. Beam ‘skirt’ measurements have been made by various researchers and this scatter is well characterised. “Point” analyses are corrupted by addition of components from the surrounding phases and x-ray maps are effectively ‘defocussed’ or ‘blurred’. The magnitude is a function of pressure, amongst many other variables, and it has been shown that these scatter effects can be reduced through extrapolation of data collected at differing chamber pressures2. Bremsstrahlung-based corrections for primary beam variations and drift have also been shown to be effective.