ELECTRON CORRELATIONS IN L-SUBSHELL PHOTOIONIZATION OF INTERMEDIATE-ZELEMENTS -LESS-THAN-OR-EQUAL-TO-Z-LESS-THAN-OR-EQUAL-TO-51)

The x-ray mass attenuation of Cd-48, In-49, Sn-50, and Sb-51 in the en ergy regime of the L-subshell edges has been measured. For a compariso n of the data of neighboring elements, these were scaled to Ag-47. The scaled data were compared with theoretical calculations of photoioniz ation cross sections by Scofield, which use the common single electron approach. The comparison reveals minor but significant deviations bet ween measurement and calculation: The measured cross sections are smal ler than the prediction in the regime between the L-3 and L-2 edges, t hey have a flatter slope in the regime between the L-2 and L-1 edges, and they exhibit a decrease just above the L-3 and L-2 edges. All obse rved deviations can be explained as electron correlation effects origi nating from a polarization of the whole electron cloud by the ionizing radiation, since they are qualitatively reproduced by comparative cal culations of the ionization process either omitting (independent parti cle approach) or including (in the linear response approximation) the electron correlations. However, the comparative calculations quantitat ively overestimate the electron correlation effects. [S1050-2947(98)04 608-3].