Nature of Anomalous X-ray Scattering and Its Application to the Structural Analysis of Crystalline and Non-crystalline Systems

Abstract

Each atom has its own absorption edges for X-rays at certain characteristic energies. Such edges represent the threshold excitation energies above which an inner electron can be ejected into the continuum states (see, for example, [1]). These X-ray absorption phenomena include predominantly the excitation of K-shell or L-shell electrons, and thus our attention focuses mainly upon the K-absorption edge or the L-absorption edge. In conventional X-ray diffraction analysis, we generally choose the energy (or wavelength, hereafter the term of energy is used) of incident X-rays away from such an absorption edge of the constituent elements, and the energy independence is then well accepted for the so-called atomic scattering factor, f(Q), given by simple potential scattering theory.