| Abstract: | The surface electronic structure of platinum is investigated by photoemission using extreme ultraviolet light. High-order harmonics of amplified femtosecond Ti:sapphire radiation in the range h =20 to 50 eV are employed. In the normal emission spectra of Pt(111), three well-distinguished maxima at fixed kinetic energies of Ekin=10,12.5 and 19eV are observed. These structures, which are far above the Fermi energy, show a strong dependence upon adsorption of CO. This observation and layer-resolved photoemission calculations indicate the surface character of the involved unoccupied platinum states. These empty states are populated by the primary photo-excited electrons, which decay into the unoccupied states due to inelastic scattering. The pronounced emission of the electrons originates mainly from these surface resonances. PACS 79.60.-i; 42.65.Ky; 71.20.-b; 79.20.Hx; 79.60.Dp |
