MATRIX CORRECTION
This is an algorithmic calculation to correct for the absorption, fluorescence and atomic number effects of other elements upon the element of interest in the material. In his 1951 Ph.D. thesis, Raymond Castaing laid out the two approaches that could be used to apply matrix corrections to the data: an empirical "alpha factor" correction for binary compounds, where each pair of elements has a pair of constant a-factors representing the effect that each element has upon the other for measured X-ray intensity; and a more rigorous physical model explicitly accounting for absorption and fluorescence in the specimen. This later approach also includes atomic number effects and became known as ZAF correction. Probe for EPMA supports the various matrix corrections, i.e., alpha, Bence Albee, and several types of both ZAF and Phi-Rho-Z algorithms. See those terms.