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P. Starowicz1,2, O. Gallus2, Th. Pillo2 and Y. Baer2
1 Institute of Physics, Jagiellonian University, Reymonta 4, 30-059 Krakow, Poland 2 Institut de Physique, Univerté de Neuchâtel, Rue A.-L. Breguet 1, 2000 Neuchâtel, Switzerland The current report presents angle-resolved photoemission data of a one-dimensional system prepared on a silicon (335) vicinal surface. Evaporated Au forms a (3x1) surface reconstruction characterised by a stable and regular steps and terraces. After deposition of Na, a one-dimensional metallic band is observed. Although the band seems to cross the Fermi level, no Fermi step is observed and the intensity diminishes approximately linearly between 50 meV and Fermi energy (EF). The unique sharp feature in the spectra is the intensity onset at EF. The discussed peak does not approach EF closer than 200 meV but gradually disappears for wave vectors exceeding kF. This situation is analogous to many other angle resolved results of one dimensional systems, for which a smooth decrease of intensity near EF is observed. The characteristic shape of our spectra can be simulated, if we assume that real one-dimensional chains are divided by defects into segments. For each segment, depending on its length a photoemission spectrum is shifted by a Coulomb energy. The distribution of chain lengths is assumed to be Gaussian. This supports the hypothesis that in reality, the defects present on the surface of a one-dimensional system divide the chains into clusters and hence Coulomb shifts contribute to the final state of photoemission. Using the proposed Coulomb shift model, one can also simulate angle integrated spectra for different types of metallic clusters deposited on insulating surfaces and the agreement with experimental data is satisfactory. |