Quantitative XRFA of Light Elements by the Fundamental Parameter Method

Abstract

SummaryAnalysis of light elements, such as C, B, and Be, differs from analysis of heavier elements by the low fluorescent yields as well as by the wide gap between their absorption edge energies and the low energy limit of the available tube-photons. Because of the fact that the (relatively large) difference between these energies is transferred to the photoelectron after an ionization event, additional excitations of light elements are very likely to occur. Other possibilities of unusual secondary excitation effects include excitation by Auger electrons and by Lα-photons after K-shell ionization. The order of magnitude of these effects has been computed for the system Fe/Fe3C. The mathematical models are based on the methods of Green and Cosslett, and Scott and Love. Results show that the C-Kα counts of pure carbon are increased by a factor 2.5-3, and count rate ratios in Fe-C binary systems increase by a factor 5-10, depending upon the experimental conditions. Fit coefficients for mass absorption coefficients of Fe and C have been calculated from experimental data collected by Saloman and Hubbel for energies between 100eV and 1keV.