Atomic Effects in the Auger and Absorption Spectra Involving the M2,3 Levels in Cr and Cr-Compounds

In the Cr-M 2,3 VV Auger spectra the autoionisation contribution increases dramatically vs. oxygen exposure and changes in shape, while in chromium silicides it becomes weaker and weaker with increasing silicon content. Similarly, the Cr-M 2,3 absorption structures, which in metal Cr are large and far in energy from the corresponding edge, in silicides become narrower and approach the edge energy. We interpret these trends as due to the concomitant effects of multiplet terms splitting, Fano-type interference and bandwidth, which are all modified on going from Cr to the compounds. The role of d -orbital occupancies in the various materials is also illustrated.