Dresden 2017 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 61: Plasmonics and Nanooptics VII: Applications and Other Aspects
HL 61.7: Talk
Wednesday, March 22, 2017, 16:30–16:45, TRE Ma
Resonant Plasmonic Antenna-Enhanced Far-IR and Terahertz Spectroscopy — •Ksenia Weber1, Maxim Nesterov1, Thomas Weiss1, Michael Scherer2, Mario Hentschel1, Jochen Vogt3, Christian Huck3, Weiwu Li4, Martin Dressel4, Harald Gießen1, and Frank Neubrech3 — 14th Physics Institute, University of Stuttgart, Stuttgart — 2InnovationLab GmbH, Heidelberg, Germany — 3Kirchhoff Institute for Physics, Heidelberg University, Germany — 41st Physics Institute, University of Stuttgart, Stuttgart
Terahertz spectroscopy is a technique with 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). In the present work we transfer the concept of SEIRA to single digit terahertz frequencies. We use plasmonic nanoantennas for the enhancement of molecular vibrations with frequencies in a spectral region from 4.5 to 45THz We therefore fabricated arrays of rectangular gold antennas by electron beam lithography and coated them with thin layers of the fullerenes C60 and C70, as well as the amino acid threonine. The samples were investigated with Fourier transform infrared spectroscopy using a bolometer as detector. An increased SEIRA enhancement of one two orders of magnitude is found for antennas resonant at 6.7THz when compared to 45THz, corresponding to a λ3 scaling.