Photoelectric cross sections of some atom-like valence levels for Mg Kα radiation and comparison with OPW estimates

Abstract

We have measured relative photoelectric cross sections of a number of loosely-bound levels, especially valence levels, of several light elements (Z < 30), using photons having an energy of 1253.6 eV (Mg Kα). Measurements were all made on solid samples of simple compounds containing the relevant elements, usually as simple ions. The results were compared with calculated cross sections for free atoms, of two types. Values were taken from Scofield's tabulation of the results of his numerical Dirac-Slater calculations. These results should be quite accurate. Cross sections were also calculated using an approach which Lohr has pointed out might be of some use, in which the photoelectron is treated as a plane wave, orthogonalized to the occupied states of the system. Neither calculation fares especially well in treating relative cross sections. Our data will, perhaps, be of interest primarily to photoelectron spectroscopists who study valence levels.