Multiplet splitting patterns exhibited by the first row transition metal oxides in X-ray photoelectron spectroscopy

High resolution photoelectron spectra from transition metal ions in TiO₂, V₂O₅, VO₂, V₂O₃, MnO, Mn₂O₃, MnO₂, Cr₂O₃, FeO, CoO, NiO, CuO, Cu₂O, FeSrO₃, and Cu doped CaTiO₃ were re-examined using a constrained curve fitting approach. Effective fits of the multiplet splitting present could be attained for the oxides with unfilled 3d bands if multiple final states were assumed. The type of transitions implied, also suggest the classification of these oxides during core level photoelectron emission as either; Mott–Hubbard (V₂O₅, VO₂, V₂O₃, Cr₂O₃, and FeO), intermediate (MnO, Mn₂O₃, and MnO₂) or charge transfer type compounds (FeSrO₃, CoO, NiO, CuO and Cu doped CaTiO₃). These transitions along with relationships defining the splitting energy with respect to the total spin and binding energy are discussed.