Photoelectron-spectroscopic study of nickel, manganese and cobalt selenides

Abstract

Photoelectron-spectroscopic studies (XPS and UPS) have been carried out to investigate electronic structure and chemical bonding in the monoselenides of nickel, manganese and cobalt. Binding-energy values and chemical shifts are reported from the XPS measurements for Ni 2p and 3s, Mn 2p and 3s, Co 2p and 3s and Se 3p and 3d. The electronic structure and bonding in the monoselenides are interpreted from an analysis of the valence-band spectra. The combined XPS and UPS data suggest transfer of electrons from the metal orbitals (Ni, Mn and Co) to selenium, contrary to bonding schemes proposed previously in the literature. Magnetic-susceptibility measurements performed by us indicate NiSe to be diamagnetic and MnSe and CoSe to be highly paramagnetic at room temperature. The presence of shake-up satellites in the XPS spectra for MnSe and CoSe and their absence for NiSe are discussed in relation to these magnetic properties.