XAS a new computer package program for X-ray absorption spectroscopy data analysis

摘要

A new version of Fourier analysis of XANES and EXAFS data obtained using synchrotron radiation, a self-contained Fortran program-package and Gnuplot with graphical data interface facilities that permits users a simple manipulation is described. By the direct dialog between the user and the Gnuplot supports, based on XANES and EXAFS spectra, there is the possibility to obtain the electronic and structural parameters. An improved procedure is used to extract more information from XANES spectra by second derivative analysis and electronic transitions distribution associated for each edge. Another purpose of the program package is based on EXAFS measurements analysis, to obtain the structural parameters: Rj - distance from the central absorbing atom to atoms in the j ~(th) coordination shell, N _j - number of atoms in the j ~(th) shell, σ _j - root mean square deviation of the interatomic distance about R _j, λ _j - mean free path for inelastic scattering, A _j - backscattering amplitude envelope function and O _j(k) - phase shift. Additional the principal component analysis allows determining the number of primary components in a set of experimental XANES or EXAFS spectra. The new computer package program was tested on different systems: supported metal catalysts, oxides and other materials.