Study on the Ti K, L_2,3, and M Edges of SrTiO₃ and PbTiO₃

The multiplet theory of free ions combined with crystal field theory is used to study core electron excitation of perovskites. This combined method is helpful to further identify transition peaks and comprehend the transition mechanism. In this paper, the core electron excitation of Ti K edge, L_2,3 edges, and M edge in SrTiO₃ and PbTiO₃ is studied, and the identification of peak and the analysis of spectral shape are emphasized. Especially at the M edge, we can identify the dipole and higher-order multiple transition peaks of Ti⁴⁺. At the L_2,3 edges, the transition strength corresponding to the 2p3d configuration coupling affects the shape of the spectra. The correction of the crystal field can make the theoretical spectra more consistent with the experimental spectra. For the K edge in PbTiO₃, by comparing the spectral shapes and energy of Ti²⁺, Ti³⁺, and Ti⁴⁺ with experiments, the spectrum is mainly composed of Ti³⁺ and Ti⁴⁺, and the proportion of Ti⁴⁺ is determined to be over 91%.