A many-body theory of the Ti M2,3-VV Auger-photoelectron coincidence spectroscopy (APECS) spectrum of TiO2(1Â 1Â 0)

► The Auger-photoelectron spectrum of TiO2(110) is calculated by a many-body theory. ► The two O 2p holes live longer than the Ti 3p hole. ► The two O 2p holes in the π bonding states are localized. ► The two O 2p holes in the σ bonding states are delocalized. ► The Coulomb repulsion from the surrounding Ti ions leads to the O+ ion desorption.