PLASMON-ENHANCED INFRARED SPECTROSCOPY OF SELF-ASSEMBLED 1-OCTADECANETHIOL MONOLAYERS
I.A. Milekhin1,2, D.A. Shcherbakov1,2, V.S. Tumashev1, S.A. Kuznetsov1,2, E.E. Rodyakina1, T.A. Duda1, A.G. Milekhin1, A.V. Latyshev1
1Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
2Novosibirsk State University, Novosibirsk, Russia
Keywords: surface-enhanced infrared absorption (SEIRA), plasmonicnanoantennas, localized surface plasmon resonance, 1-octadecanethiol, Langmuir-Blodgett films, molecular vibrational spectroscopy
Abstract
Surface-enhanced infrared absorption (SEIRA) spectroscopy, which is based on the enhancement of the infrared response of an analyte in the vicinity of plasmonic nanoantennas, is a promising technique for highly sensitive molecular detection. The development of approaches to further improve the sensitivity of this technique remains an important challenge in modern sensor technology. In this work, arrays of linear gold nanoantennas fabricated on a silicon substrate were used to detect the characteristic vibrations of monolayer coatings. 1-Octadecanethiol (ODT) was employed as a model analyte, and a layer-by-layer coating procedure based on the Langmuir-Blodgett method was implemented. Two ODT monolayers were sequentially deposited onto the Au nanoantennas, allowing the absorption enhancement factor of the ODT vibrational band at approximately 1470 cm⁻¹, assigned to the bending vibrations of CH₂ groups, to be estimated as 3×105. The obtained results demonstrate the potential of plasmonic nanoantennas for the development of mid-infrared sensors.
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