Next-nearest neighbour contributions to the XPS binding energies and XANES absorption energies of P and As in transition-metal arsenide phosphides MAs 1−yP y having the MnP-type structure

Abstract

X-ray photoelectron spectroscopic (XPS) and X-ray absorption near-edge spectroscopic (XANES) measurements have been made for several series of metal arsenide phosphides MAs 1− y P y ( M=Co, Fe, Cr) that adopt the MnP-type structure. The P and As XPS binding energies (BEs) and XANES absorption energies of the metal arsenide phosphides do not follow the trend observed for the simple binary phosphides or arsenides, a deviation that arises from the combination of nearest and next-nearest neighbour contributions acting on the P or As photoemission or absorption site. The P 2 p 3/2 BEs and K-edge absorption energies are lower in MAs 1− y P y than in MP because the P atoms are more negatively charged and because the P photoemission or absorption site is screened to a greater extent by less positively charged nearest-neighbour M atoms and more negatively charged next-nearest neighbour P atoms. The As L 3- and K-edge absorption energies are higher in MAs 1− y P y than in MAs primarily because the As atoms are less negatively charged. The M charge has been evaluated from analysis of the M 2 p XPS spectra and the M L- and K-edge XANES spectra.