Regensburg 2016 – scientific programme
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O: Fachverband Oberflächenphysik
O 33: Photonics and Nanooptics I: Infrared Spectroscopy
O 33.2: Talk
Tuesday, March 8, 2016, 10:45–11:00, H4
Plasmonic Enhancement of Infrared Vibrational Signals: Nanoslits versus Nanorods — •Christian Huck1, Jochen Vogt1, Michael Sendner1,2, Daniel Hengstler1, Frank Neubrech1,3, and Annemarie Pucci1,2 — 1Kirchhoff Institute for Physics, Heidelberg — 2InnovationLab GmbH, Heidelberg — 34th Physics Institute and Research Center SCoPE, Stuttgart
We report on investigations of nanoslit arrays as a substrate for surface-enhanced infrared absorption (SEIRA). Nanoslits, fabricated by electron beam lithography and subsequent argon ion etching, feature strong resonances in the infrared spectral range, according to Babinet's principle. The plasmonic resonances are compared to those of solid nanoantennas, with exactly the same dimensions. Compared to the nanoantenna, a nanoslit can feature several advantages, as will be discussed in the talk. The SEIRA performance is compared by investigating a monolayer of octadecanethiol. Furthermore, the slit geometry is optimized by systematically examining all important parameters. We show, that the slit width has a strong influence on the near-field intensity and therefore also on the SEIRA performance. Finally, the transversal and longitudinal coupling of nanoslits is studied and the response is compared to the excitation of a single nanoslit. A strong coupling behavior is observed, and the periodicity is optimized, leading to the maximum SEIRA signal. The coupling condition is compared to that of solid nanostructures, revealing several differences. Our results give access to general design rules for any sensing application based on the use of inverse nanostructures.