Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 85: Plasmonics and nanooptics V

O 85.8: Talk

Friday, March 30, 2012, 12:15–12:30, MA 005

Plasmonic excitations in quasi 1d structures — •Ulrich Krieg, Christian Brand, Viktoria Meier, Herbert Pfnür, and Christoph Tegenkamp — Institut für Festkörperphysik, Leibniz Universität Hannover, Appelstrasse 2, D-30167 Hannover, Germany

A quasi one dimensional system was prepared by adsorption of 0.5 Ml Ag on vicinal Si (557) via self assembly. The morphology of these single domain wire like structures was characterised by spot profile analysis LEED (SPA-LEED), STM and subsequently studied by electron energy loss spectroscopy. For the latter an instrument with both high energy and momentum resolution was used (ELS-LEED). The measured loss spectra showed a strong anisotropy: In parallel direction the plasmonic loss dispersed linearly while in perpendicular direction the plasmonic loss does not disperse at all. This can be interpreted as an electronic decoupling and subsequently a confinement of the plasmon to the nanowires of finite width.

The quantitative simulation of the plasmonic losses in the low momentum regime is compatible with a wire width of 2.5 nm which agrees well with the width of the (111) terraces of Si (557). Indeed we found with SPA-LEED and STM the overall step-structure unchanged and the step-edges undecorated after the evaporation and annealing process. This confirms the model of a quantum well perpendicular to the nanowires used in our simulations.