Using Quantitative Iteration to Correct for Pathological Spectral Interferences

Extract

A number of problematic analytical situations are known to exist in electron probe microanalysis (EPMA) where characteristic x-ray spectral overlaps are not only severe, but are also of the “self-interfering” or “cascade” variety. The “self-interfering” variety is exemplified by the innocuous Ba Lα ↔ Ti Kα; to the fearsome Pb Lα↔As Kα binaries, while “cascade” interferences are often seen among the transition metal series as in Ti Kβ → V Kα - V Kα Cr Kα or as seen with a secondary fluorescence interference effect as in Ni K ⇒ Fe Kα - Fe Kβ → Co Kα. Unlike simple interferences of the type Mn Kβ → Fe Kα, both of these types of spectral interferences are often quite troublesome for the analyst to correct for, especially for Si(Li) and Ge energy dispersive spectrometers (EDS) where the analytical peaks are often so overlapped as to prevent graphical deconvolution, and even for the higher resolution wavelength dispersive spectrometers (WDS) along with the yet to come bolometric energy dispersive detectors (based on projected resolution), the task can still be formidable.