VOIGT-BASED METHODS FOR ARBITRARY-SHAPE STATIC HYPERFINE PARAMETER DISTRIBUTIONS IN MOSSBAUER-SPECTROSCOPY

We introduce a powerful approach for obtaining arbitrary-shape static hyperfine parameter distributions from thickness corrected Mossbauer spectra. The distributions are taken to be sums of Gaussian components and the corresponding spectra are shown analytically to be sums of Voigt lines. Three cases are worked out in detail for distributions of: i) center shifts, ii) quadrupole splittings with linear coupling to center shifts, and iii) hyperfine fields with linear couplings to center shifts and quadrupole splittings. The domain of validity of our method is described, with particular attention given to recognizing the presence of dynamic effects. An application of hyperfine field distributions to the spectra of Fe-Ni alloys is given. In all cases, convergence is rapid and unambiguous with only two or three Gaussian components being needed for ideal fits. Adding more components does not destabilize the solution but only results in the same distribution and the same values of all the parameters being obtained. Problems occurring with other methods are eliminated by design - given the intrinsic suitability of an expansion in terms of Gaussians.