This allows the character of the ionic states in terms of the occupations of the open shell core and valence orbitals and of the contributions of 2p 1/2 and 2p 3/2 ionization to the XPS intensities to be determined. This orbital selection makes it possible to treat both the angular momentum coupling of the open shell core and valence electrons as well the shake excitations from the closed shell orbitals associated with the O ligands into the valence open shell orbitals associated with the Fe 3d shell. This has been possible using a unique methodology for the selection of orbitals that are used to form the ionic wavefunctions. This paper presents a rigorous ab initio treatment of the main and satellite features in the Fe 2p XPS of Fe 2O 3. Although the origin and assignment of the complex XPS features of the cations in ionic compounds has been the subject of extensive theoretical work, agreement with experimental observations remains insufficient for unambiguous interpretation.
