Bonding in SiO₂ and Fe₂O₃ by Oxygen K_α X-ray Emission Spectra

Abstract

SILICON in tetrahedral and iron in octahedral coordination are fundamental units in a wide range of silicate minerals. Thus investigations of the nature of the Si–O and Fe–O bond in simple oxides such as SiO₂ and Fe₂O₃ may provide some basis for the better understanding of these bonds in more complex silicate structures. Recently, attempts have been made to interpret certain aspects of the L_II,III X-ray emission spectra of some transition metal compounds^1–3 and the K_β spectra of third row metal compounds^3–5, using molecular orbital (MO) theory. Initial results have been most encouraging and MO theory seems to have great potential in the interpretation of spectra arising from transitions from valence orbitals. We present here the initial results of investigations of oxygen K_α emission spectra from SiO₂ (quartz) and Fe₂O₃ (haematite), which are readily interpretable within the framework of simple MO theory.