Chemisorption state of atomic oxygen on TiC(100) surface: angle-resolved photoemission study

Abstract

Angle-resolved photoemission spectroscopy with synchrotron radiation has been used to study oxygen adsorption on a TiC(100) surface at room temperature. Oxygen is adsorbed dissociatively, and the O 2p-derived states of atomic oxygen are found at 4.1 and 5.9 eV at the Γ̄gG point. From polarization-dependent measurements, these states are assigned to the 2p x,y - and 2p z -derived states, respectively. Two-dimensional band dispersions of these states in the Γ̄gGM̄ direction are mapped from the off-normal-emission measurements. The measured band structure suggests that the 2p z orbital is relatively more stabilized through the chemisorption bonding. The cross section of the O 2p-derived states does not show a resonance at the energy region of the Ti3p-3d transition threshold, indicating that a hybridization of the Ti3d and O 2p orbitals contributes little to the chemisorption bonding. These results are compatible with the C on-top site adsorption model.