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The surface structure of the so-called Ag/Si͑111͒-(6ϫ1) surface is studied by low-energy electron diffraction ͑LEED͒, high-resolution core-level photoelectron spectroscopy, and angle-resolved photoelectron spectroscopy. A c(12ϫ2) phase is observed in LEED after cooling the room-temperature (6ϫ1) phase to 100 K. In the Si 2p core-level spectra, no significant difference is observed between the two surfaces. In the valenceband spectra, five surface states are observed on both the (6ϫ1) and c(12ϫ2) surfaces. None of these surface states crosses the Fermi level. The binding energies and dispersions of the surface states observed on the (6 ϫ1) surface are quite similar to those of the c(12ϫ2) surface. These results indicate that the basic structure of this Ag/Si͑111͒ surface has a c(12ϫ2) periodicity, and that the (6ϫ1) structure results from thermal vibrations of the surface atoms. Moreover, we assign two of the surface states to bonding states between Ag and Si atoms, and one of them to a -bond state.

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The structure of low coverage Ni atoms on the TiO2(110) surface was studied using polarization dependent EXAFS. We found that Ni atoms interacted with oxygen atoms at the n 1 1 step edges, where atomically dispersed Ni species were found with Ni-O distances at 0.199 ± 0.002 nm and 0.204 ± 0.003 nm in parallel and perpendicular directions to the Koike et. al. 2 TiO2(110) surface, respectively. The location corresponded to the virtual Ti site if the next TiO2 layer was created on the topmost TiO2 surface. The Ni location is mainly determined by the dangling bond directions of the surface oxygen atoms.

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