Tailoring plasmonic substrates for SERS

Abstract

SERS is a useful spectroscopic technique that was discovered 30 years ago, and has recently seen a renaissance in research. Sphere segment void (SSV) substrates have been developed as reproducible, stable SERS substrates by electrodeposition of a metal through a colloidal template.
The effect of adsorbing an organic monolayer on the surface of an SSV substrate was studied, which results in a slight shift in the plasmonic absorption. This was compared with the reduction of a diazonium salt on the surface, which results in a significant increase in plasmonic absorption, attributed to a physical sharpening of the metal structure, and in turn better defined plasmon modes.
The Au surface was also modified with an ultra thin layer of Pt, and a comparison was made between oxidation-reduction cycled roughened (ORC) and SSV substrates with and without Pt. The SSV substrates were found to be more reproducible, and (after modification with a thin-layer of Pt), gave spectra more representative of bulk Pt substrates than ORC.
Lastly the surface was functionalised with metallic nanoparticles (NPs), and a large increase in spectral intensity was observed. This was attributed to a strongly localised electric field between the NP and the substrate, which resulted in an additional enhancement of between 102-103 depending on the method of assembly used. Functionalisation of the NPs introduced the possibility of drug detection or studies in drug delivery using such a system

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Identifiers

ORCID for Andrea E. Russell: orcid.org/0000-0002-8382-6443

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