CHEMISORPTION STATE OF ATOMIC OXYGEN ON TIC(100) SURFACE - ANGLE-RESOLVED PHOTOEMISSION-STUDY

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 GAMMABAR 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 GAMMAMBAR 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 Ti 3p-3d transition threshold, indicating that a hybridization of the Ti 3d and O 2p orbitals contributes little to the chemisorption bonding. These results are compatible with the C on-top site adsorption model.