Angle-resolved photoemission study of the surface state on TiC(111)

Angle-resolved photoemission spectroscopy utilizing synchrotron radiation has been used to study the electronic structure of a ${\mathrm{TiC}}_{0.96}$(111) surface. A sharp emission from a surface state is observed at just below the Fermi level (0.20 eV at the Γ¯ point) which is rapidly quenched by hydrogen adsorption. In addition, a weak emission peak is observed at 0.55 eV, which is also derived from the polar structure of the (111) surface but is insensitive to hydrogen adsorption. The two-dimensional band dispersion of the surface state is not found directly, but off-normal-emission measurements suggest that the state disperses upwards for both the Γ¯→M¯ and Γ¯→K¯ directions above the Fermi level. A resonant enhancement of the surface-state emission is found at hν∼45 eV.