The TaC(100) surface has been explored with spin-resolved photoemission using circularly polarized light from the Berlin storage ring BESSY. Initial states with a spin-orbit splitting of 0.45 eV were observed. Their identification as ${\Delta }_5$-type bulk bands suggests a rearrangement of the Fermi level in the relativistic band structure of tantalum carbide. With lower intensity additional structures of the same symmetry were found at lower binding energies, which cannot be understood in terms of direct bulk transitions. These peaks are interpreted as emission from states induced by carbon vacancies. A weak structure close to the Fermi energy is attributed to a surface resonance.

• Received 11 July 1988

DOI:https://doi.org/10.1103/PhysRevB.39.6115