A New Technique to Determine Amorphous Structure Using X-Ray Absorption Fine Structure

摘要

A new theory for extended x-ray absorption fine structure (EXAFS) is presented which treats EXAFS as arising from the scattering of the ejected photoelectron by atoms surrounding the absorbing atom. The surrounding atoms are treated as a system of weak point scatterers which allows the scattered waves to be calculated using standard scattering theory. These scattered waves are included in the wave function of the ejected photoelectron and this is used to calculate the dipole transition matrix element from the x-ray absorption, which gives rise to oscillations in the absorption coefficient which depends on the positions of the surrounding atoms. The final result includes scattering factor, range and temperature terms and is general enough to handle any symmetry of atoms about the absorbing atom and any polarization state of the x-rays. (Author)