IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Friday Sessions
       Session SS1-FrM

Paper SS1-FrM2
Dimensionality Investigation of an Alloy-dealloy Phase Transition on Ag/Cu(110)

Friday, November 2, 2001, 8:40 am, Room 120

Session: Dynamics of Metal Surfaces
Presenter: P.T. Sprunger, Louisiana State University
Authors: O. Kizilkaya, Louisiana State University
D.A. Hite, Louisiana State University
J. Choi, Louisiana State University
P.T. Sprunger, Louisiana State University
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An alloy-dealloy phase transition as a result of 0.4-1 ML deposition of Ag on Cu(110) has been studied by use of angle resolved photoemission spectroscopy (ARUPS). The ARUPS measurements were performed at 3m. TGM beamline at Center for Advanced Microstructure and Devices synchrotron facility. Previous scanning tunneling microscopy studies showed that a surface alloy phase seen at submonolayer coverages of Ag (<0.4 ML) evolves into well ordered Ag chains at higher coverages. These chains consist of Ag dimers and trimers directed on [001] of the substrate and located on monomer and dimer [001] directed vacancies.The ARUPS results for 1 ML coverage of Ag revealed that this unique chain geometry has near 1-dimensional electronic structure showing dispersion along the Ag-chains with no dispersion perpendicular to chains and no dispersion as a function of varying photon energy. The ARUPS were measured in two different geometries, specifically, the vector potential, A, was parallel and perpendicular to [001] plane of Cu(110) in which chain structure was directed. The energy distrubition curves (EDC) as a function of photon energy show the lack of dispersion which imply that Ag chains are not incorporated into Cu(110) substrate. Although no perpendicular dispersion is observed, ARUPS data confirms, by changing the emission angle in surface Brillouin zone along the two high symmetry lines, that the Ag bands in-plane (parallel to the surface) anisotropically disperse. In the experimental geometry probing electronic geometry parallel to the Ag structural chains, that is along the [001] direction of the substrate, the Ag bands disperse as a function of parallel momentum. In contrast, with the experimental geometry probing electronic structure perpendicular to the [001] direction, there is little to no dispersion of the Ag d-bands.These results signify reduced dimensional electronic structure of Ag chains. Research was supported by U.S. DOE contract No. DE-FG02-98ER45712.