Berlin 2008 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 88: Metallic Nanostructures II (on Semiconductors)
O 88.3: Vortrag
Freitag, 29. Februar 2008, 10:00–10:15, MA 005
Anisotropic Photoemission from Faceted Au Clusters on Graphite — •Ingo Barke1, Heinz Hövel2, Farhad Ghaleh2, Richard C. Hatch3, and Hartmut Höchst3 — 1Universität Rostock, Universitätsplatz 3, D-18051 Rostock — 2Technische Universität Dortmund, Otto-Hahn-Str. 4, D-44221 Dortmund — 3Synchrotron Radiation Center, 3731 Schneider Dr., Stoughton, WI 53589, USA
Quantized Shockley surface states have been observed on hexagonal facets of large Au clusters by means of scanning tunneling spectroscopy [1] and photoelectron spectroscopy [2]. Here we report on recent results obtained by angle resolved photoelectron spectroscopy (ARPES) with synchrotron radiation at the Synchrotron Radiation Center in Stoughton, WI (USA). Optimized preparation parameters resulted in narrow size distributions which allow for the direct observation of the size-dependent peak distance of quantized states. Angle resolved spectra reveal another striking difference between cluster facets and the bulk surface: we observe an unexpected asymmetry of emission intensity with respect to the emission angle which is very sensitive to the photon energy. With a suppression of almost 100% for one of the two branches of the parabolic dispersion this effect is much stronger and of opposite sign compared to the bulk Au(111) surface state.
[1] I. Barke, H. Hövel, Phys. Rev. Lett. 90, 166801 (2003).
[2] H. Hövel, I. Barke, Prog. Surf. Sci. 81, 53 (2006).