A total current spectroscopy study of metal oxide surfaces: II. Unoccupiedelectronic states on TiO2(110) and SrTiO3(100) surfaces

Unoccupied densities of states (DOS) for the ordered and atomically clean T iO2(110) and SrTiO3(100) surfaces were studied using the total current spec troscopy (TCS) technique. Obtained TC spectra reveal the Ti-derived (Ti 3d( e(g))-5.2 eV, Ti 4s-23.5 eV) and Sr-derived (Sr 3d-triplet: 7.3, 9.0 and 10 .5 eV; Sr 5p/O 2p-15 eV) maxima of unoccupied DOS. Main oxygen-derived maxi ma are located at 11.2 and 15.0 eV for TiO2 and at 11.8, 18.0 and 19.6 eV f or SrTiO3. The results are discussed in comparison with the previously repo rted data on DOS of these materials and they provide additional detailed in formation on the energy structure of unoccupied DOS on TiO2(110) and SrTiO3 (100) surfaces in the 4-25 eV range above the Fermi level.