A many-body theory of the Ti M 2,3-VV Auger-photoelectron coincidence spectroscopy (APECS) spectrum of TiO 2(1 1 0)

Abstract

We calculated the Ti M 2,3-VV Auger-photoelectron coincidence spectroscopy spectrum of TiO 2(1 1 0) by a many-body theory. The spectral main line is governed by the DOS of the two O 2p holes living longer than the Ti ∣ cd 2 L 2〉 → ∣ L 2〉 super Coster-Kronig (sCK) decay. The two O 2p holes are created by the charge transfer core–hole screening at the Ti atomic site. Here c and L are the Ti 3p hole and the ligand O 2p hole, respectively. Analysis of the spectrum shows that the two (or three) CT O 2p holes in the π bonding states are localized, whereas those in the σ bonding states are delocalized. The three localized CT O 2p ( π) holes in ∣ cd 3 L 3〉 in Ti M 2,3 main line (or satellite) of TiO 2(1 1 0) live longer than the Ti ∣ cd 3 L 3〉 → ∣d 1 L 3〉 sCK decay so that the Coulomb repulsion from the surrounding Ti ions gives the O + ion desorption from the surface.