X-Ray emission and photoelectron spectra from magnesium oxide: a discussion of the bonding based on the unit Mg4O4

Abstract

A simple molecular-orbital model for the bonding in magnesium oxide is developed using Mg₄O₄(a cube with magnesium and oxygen atoms at alternate corners) as a basis. Extension to Mg₃₂O₃₂ indicates how the molecular-orbital description of Mg₄O₄ can be developed into the band structure for MgO. The qualitative predictions concerning the distribution of Mg 3p, Mg 3s, O 2p, and O 2s character amongst the various orbitals are checked by comparison with X-ray emission (Mg-K_β1,3, Mg-L_2,3 M, and O-K_α) and also X-ray photoelectron spectra. The Mg₄O₄ model provides an adequate rationalisation of the principal features of the spectra, particularly of the split magnesium X-ray emission peaks.