When the valence charge is removed or transferred from the atom, the screening is reduced. As a result, the screening is reduced; the cation-core electrons are attracted more strongly to the nucleus. Thus all inner (core) levels of an atom are shifted by fractions of 1 eV to a few eV when the valence electron configuration changes on bonding.The binding energy increases (decreases) if electrons are lost (gained). In our case, when the Ti4+ transfer to Ti3+, one electron is gained. As a result, the binding energy of Ti 2p3/2 decreases about 1 eV