Oxygenation mediating the valence density-of-states and work function of Ti(0001) skin.

Consistency between density function theory calculations and photoelectron spectroscopy observations confirmed predictions based on the framework of bond-band-barrier (3B) correlation notation [Sun, Prog. Mater. Sci., 2003, 48, 521-685] that an oxygen adsorbate interacts with Ti(0001) skin atoms to form a tetrahedron with creation of four valence density-of-state features: O-Ti bonding electron pairs, O nonbonding lone pairs, Ti electronic holes, and Ti antibonding dipoles. Formation of the dipoles lowers the work function of the Ti(0001) skin and electron-hole generation turns the metallic Ti(0001) into the semiconductive O-Ti(0001). Findings confirm the universality of the 3B correlation in understanding the dynamics of oxygen chemisorption and the associated valence electrons involved in the process of oxidation.