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.