Electronic structure of the (1×1) oxygen overlayer on TiC(111): Angle-resolved photoemission study

Abstract

Angle-resolved photoemission spectroscopy with synchrotron radiation has been used to study the electronic state of oxygen adsorbed on a TiC(111) surface at room temperature. Oxygen is adsorbed dissociatively forming a (1\ifmmode\times\else\texttimes\fi{}1) overlayer on the TiC(111) surface at saturation coverage. The band structure of the (1\ifmmode\times\else\texttimes\fi{}1)-O overlayer is measured in the two symmetry directions; 〈21\ifmmode\bar\else\textasciimacron\fi{} 1\ifmmode\bar\else\textasciimacron\fi{}〉(\ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} M\ifmmode\bar\else\textasciimacron\fi{}) and 〈011\ifmmode\bar\else\textasciimacron\fi{}〉(\ensuremath{\Gamma}\ifmmode\bar\else\textasciimacron\fi{} K\ifmmode\bar\else\textasciimacron\fi{}) of the TiC(111) surface. The binding energy of the O 2${\mathit{p}}_{\mathit{z}}$-derived band is always lower than those of the O 2${\mathit{p}}_{\mathit{x}}$- and O 2${\mathit{p}}_{\mathit{y}}$-derived bands throughout the surface Brillouin zone, indicating that the 2${\mathit{p}}_{\mathit{x}}$ and 2${\mathit{p}}_{\mathit{y}}$ orbitals are more important for the chemisorption bond formation.