Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 5: Plasmonics: Nanoantennas, Nanoparticles
O 5.3: Vortrag
Montag, 16. März 2015, 11:00–11:15, MA 042
Gold Nanoantennas with Reduced Substrate Contact for Plasmonic Enhancement in the Infrared — •Christian Huck1, Andrea Toma2, Frank Neubrech1,3, Manohar Chirumamilla2, Jochen Vogt1, Francesco De Angelis2, and Annemarie Pucci1 — 1Kirchhoff Institute for Physics, University of Heidelberg, Germany — 2Istituto Italiano di Tecnologia, 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 enables strong vibrational signal enhancement in the infrared. Commonly used substrates for surface enhanced infrared absorption (SEIRA) consist of meal nanoparticles located on a dielectric substrate. However, this planar arrangement substantially weakens plasmonic resonances because of the substrate polarizability and, furthermore, a great part of the electromagnetic near-field is located inside the substrate and thus not accessible for enhanced vibrational spectroscopy of an analyte. In this contribution we present one way to reduce the undesirable influences of the substrate by fabricating gold nanowires situated on a silicon pedestal and therefore in a reduced contact with the substrate. The influence of the pedestal height is studied by finite-difference time-domain simulation and plays a crucial role for the optimization of near-field intensities. Furthermore we show a comparison of the plasmonic response as well as the SEIRA activity between rods prepared by standard electron beam lithography and rods which were additionally treated with reactive ion etching to remove the silicon substrate around the hot-spots of the rods.