Optimization of parameters in electron probe microanalysis

RITA BONETTO; GUSTAVO CASTELLANO; JORGE TRINCAVELLI

X-RAY SPECTROMETRY

JOHN WILEY & SONS LTD

Año: 2001 vol. 30 p. 313 - 319

0049-8246

A method for refinement of atomic and experimental parameters is presented, applicable to several spectroscopic techniques. This kind of procedure, previously used in x-ray diffraction, is shown as a powerful tool in Electron Probe Microanalysis (EPMA). This method consists of minimizing the differences between an experimental x-ray spectrum and a function proposedto account for the bremsstrahlung and characteristic peaks from the corresponding sample, as well as for detection artifacts. This complicated function involves several parameters related to different sources (x-ray production, x-ray attenuation, sample composition, x-ray detection, etc.).Initial values must be supplied for them, and after a numerical iterative procedure is performed, improved values are achieved. Depending on the particular situation, certain parameters may be known a priori, so that they can be fixed allowing the others to vary. In this way, the methodcan be used for different purposes: determination of atomic parameters such as fluorescence yields, transition rates or photoelectric cross-sections; quantitative standardless analysis; determination of detector characteristics, etc. This work is intended to present the general aspects of the method for refining EPMA parameters, as well as to give some examplesof its application to the aforementioned issues. Even when only EPMA spectra are included in this work, the method can be applied to different spectroscopic techniques, such as x-ray fluorescence, particle-induced x-ray emission, etc.