Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 37: Posters: Plasmonics, Electronic Structure and Spin-Orbit Interaction, Semiconductor and Insulator Surfaces, Nanostructures
O 37.1: Poster
Dienstag, 1. April 2014, 18:30–22:00, P2
Free-standing gold nanoantennas for enhanced infrared spectroscopy — •Christian Huck1, Andrea Toma2, Frank Neubrech1,3, and Annemarie Pucci1 — 1Kirchhoff-Institute for Physics, Heidelberg, Germany — 2Istituto Italiano di Tecnologia (IIT), Genova, Italy — 34th Physics Institute and Research Center SCoPE, Stuttgart, Germany
Plasmon-polariton excitations of metal nanoparticles can couple to other excitations of similar energy, which gives rise to strong vibrational signal enhancement in the infrared. For a optimization with respect to the enhancement it is necessary to carefully design the optical properties of the antenna, e.g. by the geometry of the structure but also by the supporting substrate. Plasmonic nanostructures prepared on substrates with high refractive indices, such as silicon and zinc sulphide, feature lower quality factors, a lower extinction cross-section and a red-shifted resonance position compared to the low refractive index substrates glass and calcium fluoride. This behavior can be explained by induced screening charges in the substrate, leading to a more damped electron oscillation in the nanorods and thus to lower vibrational signal enhancements in SEIRS. In this contribution we present one way to reduce the undesirable influences of the substrate by fabricating elevated gold nanowires which are only partly in contact with the substrate. We show a comparison of the plasmonic response as well as the SEIRS activity between rods prepared by standard EBL and rods which were additionally treated with reactive ion etching to remove the silicon substrate around the hot-spots of the rods.