Analysis of the x-ray photoelectron energy-loss background in silicides

Intermetallic compounds provide a means to investigate the mutual influence of two elements on the photoelectron fine structure and background that ha ve developed as a result of bond formation. In the case of the aluminides w e have shown that aluminium acquires a background structure that is typical of elements having a 3d valence band and concluded that there is a strong 'd' component in the bonding structure arising from pd hybridization. In th is paper we report a similar analysis of the background structure in two si licides, MoSi2 and FeSi2. Both silicon and molybdenum in MoSi2 are very similar in background structu re to that in their respective pure elemental states. Moreover, the plasmon structure that appears is similar to that of silicon itself. Thus we concl ude that in this material 'p' character is an important feature of the bond . In the case of FeSi2 the situation is different. Here, silicon gains a pr onounced background step, similar to that of iron, and the plasmon structur e becomes weaker. This behaviour is analogous to that of FeAl and we conclu de that this is evidence of the participation of the 'd' states of iron in bond formation. Copyright (C) 2001 John Wiley & Sons, Ltd.