Regensburg 2016 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 33: Photonics and Nanooptics I: Infrared Spectroscopy
O 33.4: Vortrag
Dienstag, 8. März 2016, 11:15–11:30, H4
Towards Resonant Plasmonic Antenna-Enhanced Terahertz Spectroscopy — •Ksenia Weber1, Frank Neubrech1, Mario Hentschel1, Michael Scherer2, and Harald Gießen1 — 14th Physics Institute and Research Center SCoPE, University of Stuttgart, Stuttgart — 2InnovationLab GmbH, Heidelberg, Germany
Terahertz spectroscopy is a technique with the potential for a vast range of sensing applications based on material-specific absorption features of molecular vibrations. However, the low absorption cross section of these excitations strongly limits its sensitivity. The possibility to increase the sensitivity of spectroscopic methods via the enhanced electromagnetic near fields provided by plasmonic nanoantennas has been shown before for surface-enhanced infrared spectroscopy (SEIRA). Our goal is to transfer the concept of SEIRA to terahertz frequencies. Here, we take a first step towards resonant antenna-enhanced terahertz spectroscopy by using plasmonic nanoantennas for the enhancement of molecular vibrations with frequencies towards the terahertz regime. We therefore fabricated arrays of rectangular gold antennas by electron beam lithography and coated them with a 30 nm thick layer of the fullerenes C60 and C70, respectively. The resonances of the structures were tailored to match the molecular vibrations located around 16 THz. The samples were investigated with Fourier transform infrared spectroscopy using a bolometer as detector. Compared to reference measurements with a pure molecular layer, an enhancement factor of four orders of magnitude is found. Our technique is a first step towards plasmon-enhanced terahertz sensing with unprecedented sensitivities.