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Photoemission spectra measured as a function of exit angle reflect the phenomenon of photoelectron diffraction (XPD), which is related to the underlying crystallographic structure of the sample. We have studied a number of systems involving ultra-thin metallic layers on surfaces. In some cases, these surface systems involve true surface alloys, whose properties are often very different from those
in the bulk. Our choice of surface systems involves the questions of elucidating surfactant behavior, catalytic activity and intercomponent effects. Our crystallographic results were derived from photoelectron diffraction in combination with LEED: derivation
of the results requires comparison with multiple scattering theoretical simulations and involve considerable computational effort. Here, we present representative results for In, Sn and Sb on Pd(111) and Ni(111), all of which form surface alloys, and discuss the structure dependence on the component atoms.
Acknowledgments: We would like to thank Fapesp, CNPq, CAPES and the LNLS of Brasil for support.
References: 1. "Photoelectron Diffraction from Random Surface Alloys Critique of Calculational Methods", E.A.Soares, A. de Siervo, R.Landers and G.G.Kleiman, Surface Science 497, 205-213 (2002).
2. "Pd on Cu (111) Studied by Photoelectron Diffraction",A. de Siervo, E.A. Soares, R. Landers, T.A. Fazan, J. Morais and G.G. Kleiman, Surface Science 504, 215-222 (2002).
3. "Photoelectron Diffraction studies of the Pd(111) and Cu
on Pd(111) random surface alloys", A. de Siervo, E. A. Soares, R. Landers, and G. G. Kleiman, Physical Review B 71, 115417-1 to 115417 -7 (2005).
4. "Growth study of Cu/Pd(111) by RHEED and XPS", A. de Siervo, R.
Paniago, E. A. Soares, H.-D. Pfannes, R. Landers,G.G. Kleiman, Surface Science 575, 217-222 (2005).
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