Regensburg 2010 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 23: Plasmonics and Nanophotonics I (Joint Session with DS/O)

HL 23.8: Talk

Tuesday, March 23, 2010, 12:15–12:30, H2

Interaction effects of gold nanoantenna arrays in the infrared — •Daniel Weber¹, Frank Neubrech¹, Dominik Enders², Tadaaki Nagao², and Annemarie Pucci¹ — ¹Kirchhoff Institute for Physics, University of Heidelberg, Germany — ²National Institute for Materials Science, Tsukuba, Japan

Gold nanoantennas are of great interest for applied spectroscopy due to their tuneable plasmonic properties including local electromagnetic (EM) field enhancement (FE). Excited resonantly by EM radiation, they are able to strongly enhance the local EM field. In the past, we exploited this strong effect for surface-enhanced infrared spectroscopy (SEIRS) with gold nanoantennas. We want to further improve the sensitivity of SEIRS by making use of nanoantenna coupling. Coupling may increase local FE but also strongly modify the spectral distribution of the FE, which provides further options for optimum resonance tuning as necessary for specific sensor applications.

We report on the IR optical properties of gold-nanoantenna arrays with different gap sizes and show the relation between plasmonic resonances and geometrical arrangement on the substrate. Stripe-like, polycrystalline gold nanoantennas (nanorods) with rectangular cross-sections were produced by electron beam lithography on silicon wafers. IR measurements were performed by micro-spectroscopy in our laboratories and at the synchrotron light source ANKA (Karlsruhe Institute of Technology). Special focus is on the preparation of very small gaps between the tip ends of nanorods, where the highest local FE is expected.