X-ray photoelectron spectra and bonding in transition-metal phosphides

X-ray photoelectron spectra of solid ScP, TiP, VP, MnP, and FeP have been obtained in the valence-conduction band region and for the 2p/sub 3/2/ core levels of both metal and phosphorus. The results show a regular increase in photoelectron intensity near the Fermi energy and a regular decrease in core level shifts relative to the elements across the series. These are interpreted as arising from a decreasing ionicity coupled with increasing metallic character accompanying the increasing number of metal d electrons.