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oa Electron Beam Stability in Routine Microprobe Analysis of Minerals: Problems and some Simple, but Optimal Solutions
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 18th International Conference Monitoring of Geological Processes and Ecological Condition of the Environment, Apr 2025, Volume 2025, p.1 - 5
Abstract
Achieving high precision and accuracy in routine EPMA analyses is often hindered by potential electron beam instability, especially under adverse operational conditions. Current study introduces a simple yet effective procedure that compensates for beam fluctuations via monitoring the measurement process with a reference sample (Cu). In this approach, two correction coefficients, k1 and k2, are applied to adjust the measured elemental concentrations. K1 is the ratio of the Cu control measurement, obtained several times during the session, to the initial Cu measurement taken at its beginning (average content values in wt% from 3–4 runs were used). This factor accounts for the impact of time since the session began, with a polynomial equation k1 vs T (minutes) used to determine an individual k1 value for each analytical result correction. K2 reflects how much the initial Cu measurement deviates from the certified standard concentration (100 wt%), so apply to ensuring consistency across sessions. Validation using a large dataset – the Cu standard as an “unknown sample” was analyzed, n = 249 – demonstrates that correction reduces deviations from the certified concentration with over 10 rel% to approximately 1,5 rel% for single measurements and to below 0,75 rel% for averaged (n=3–4) data.
