Free-standing optical gold bowtie nanoantenna with variable gap size for enhanced Raman spectroscopy.

Hatab, Nahla A; Hsueh, Chun-Hway; Gaddis, Abigail L; Retterer, Scott T; Li, Jia-Han; Eres, Gyula; Zhang, Zhenyu; Gu, Baohua · Nano Lett · 2010

basic_science · Level V

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Abstract

We describe plasmonic interactions in suspended gold bowtie nanoantenna leading to strong electromagnetic field (E) enhancements. Surface-enhanced Raman scattering (SERS) was used to demonstrate the performance of the nanoantenna. In addition to the well-known gap size dependence, up to 2 orders of magnitude additional enhancement is observed with elevated bowties. The overall behavior is described by a SERS enhancement factor exceeding 10(11) along with an anomalously weak power law dependence of E on the gap size in a range from 8 to 50 nm that is attributed to a plasmonic nanocavity effect occurring when the plasmonic interactions enter a strongly coupled regime.