(1×1) rippled relaxation of (100) transition-metal carbide surfaces

An investigation of (100) surfaces of TaC and HfC was performed using low-energy electron diffraction (LEED) and angle-resolved ultraviolet photoemission spectroscopy with synchrotron radiation. Detailed LEED I–V analyses show that, on both surfaces, carbon atoms displace outward and metal atoms inward, giving rise to (1×1) rippled relaxations, with the magnitude of the ripple being larger on TaC(100). Photoemission spectra of metal 4f levels from these surfaces show no obvious surface core-level shifts. Using x-ray photoemission spectroscopy (XPS) and Auger electron spectroscopy (AES), changes in (bulk) core-level binding energies, valence-band structures, and local carbon environments were determined for TaCx (0.5