Oxygen adsorption on aNbC0.9(111) surface: Angle-resolved photoemission study

Angle-resolved photoemission spectroscopy utilizing synchrotron radiation has been used to study the adsorption of oxygen on a NbC(111) surface at 80 K. Oxygen is adsorbed dissociatively forming a (1×1) overlayer on the NbC(111) surface. The O 2p–derived states are found at 1.0 and 2.6 eV below the Fermi level in normal-emission spectra. From polarization-dependent measurements, these states are assigned to the 2${\mathit{p}}_{\mathit{z}}$- and 2${\mathit{p}}_{\mathit{x},}$y-derived states, respectively. Two-dimensional band dispersions in the Γ¯–M¯ direction of these states are determined from the off-normal-emission measurements. The experimentally determined dispersive features of the 2${\mathit{p}}_{\mathit{z}}$- and 2${\mathit{p}}_{\mathit{x},}$y-derived states can be understood in terms of a simple tight-binding picture.