ELECTRONIC-STRUCTURE INVESTIGATION OF CU(001)-P(2X2)S USING ANGLE-RESOLVED PHOTOEMISSION AND INVERSE-PHOTOEMISSION

Angle-resolved photoemission (ARPE) and inverse photoemission (ARIPE) are used to measure the dispersion of sulfur-induced electronic surface bands of the Cu(001)-p(2 x 2)S surface. Polarized synchrotron and rare-gas resonance radiation is used to identify the symmetry and the atomic origin of the three sulfur 3p-like bonding states between -4.9 and -5.4 eV below the Fermi energy, as well as of occupied antibonding Cu 3d-like states split off from the bulk d states to higher energy. The surface-band structure of the odd-symmetry states along the DELTABAR line of the Brillouin zone is interpreted in terms of a simple tight-binding LCAO picture, which takes into consideration only nearest-neighbour interactions between S 3p orbitals in the fourfold hollow adsorption site and neighbouring Cu 3d orbitals in the surface plane. Two unoccupied S-induced states at +1.4 and +12.5 eV are detected. Using photoionization cross-sections, found in the literature, the latter is ascribed to S 3d. The work function (deduced from ARPE spectra) in dependence of the sulfur coverage is also given.