Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 34: Poster Session I (Graphene; Plasmonics and nanooptics; Coherence and coherent control in nanophotonics and plasmonics)

O 34.55: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster E

Surface passivation and dark field spectroscopy of metallic nanocones — •Dominik Gollmer, Christian Schäfer, Yuliya Fulmes, Andreas Horrer, Dieter P. Kern, and Monika Fleischer — Institut für Angewandte Physik, Eberhard Karls Universität Tübingen, Auf der Morgenstelle 10, 72076 Tübingen

The external electromagnetic excitation of plasmonic nanostructures is accompanied by a localized enhanced near field, which makes these structures promising candidates for several applications like near-field imaging or sensing. We fabricated conical nanostructures with sharp tips (tip radii less than 10 nm) [1] using different unique fabrication methods. Because of their shape, these nanocones are suitable candidates for the applications mentioned above. The tunability of the optical properties of nanocones is an important precondition for efficient excitation. We showed via dark field spectroscopy of single structures that this can be achieved by variation of size, aspect ratio and material. For non-stable materials a passivation is essential to keep the optical properties constant over time. Aluminum oxide has been suggested as an appropriate material for this purpose [2]. We showed that it is possible to passivate silver nanocones by oxidized thin sputtered aluminum layers. The fabrication processes will be presented together with dark field images and spectra of gold and silver nanocones in different sizes. The changes in unprotected and passivated silver cones with time will be illustrated by SEM and dark field images. [1] M. Fleischer et al.; Nanotechnology 21 (2010); 065301 [2] C. A. Barrios et al.; The Journal of Physical Chemistry C 113 (2009); 8158-8161