Universal X-ray edge behaviour in alkali metals and their alloys

Abstract

Reports results of a systematic experimental investigation of Cs 5p, Rb 4p and K 3p core excitation spectra in alkali-alkali alloys containing these atomic species. Various excitation profiles at threshold are observed. These apparently belong to a universal sequence of lineshapes. It is possible to predict which lineshape occurs in any particular alloy using a parameter xi which is a ratio of potential to kinetic energy in the excited configuration. An 'X-ray edge anomaly' occurs only in one limit of the sequence, namely xi large.