Linear and non‐linear peak fitting in energy‐dispersive X‐ray fluorescence

Abstract
Linear and non‐linear least‐squares fitting procedures are compared in their ability to resolve X‐ray fluorescence spectra obtained with Si(Li) detectors. It is shown, by repeated analysis of synthetic and real X‐ray spectra, that non‐linear least‐squares fitting programs which take into account the relation between peak positions and widths on the one hand and X‐ray energies on the other hand, and moreover impose limitations upon the fitting parameters, represent a definite advantage over the linear least‐squares fitting method. Only for spectrometers having an extremely high stability with time and counting rate does the linear fitting procedure yield accurate results.