Detection of nitrogenous and nitro-aromatic compound with thin gold films roughened by cold argon plasma as SERS-active substrate

Abstract

Surface Enhanced Raman spectroscopy (SERS) is a fast, accurate and sensitive technique for detection of analyte in trace quantities. Design and fabrication of SERS-active substrate plays a vital role in the enhancement of a Raman signal and hence it is a matter of great research interest. Here, we present the design of a large-area SERS-active substrates by modifying thin gold (Au) film on silicon (Si) by irradiating it with argon ions (Ar+) at optimized parameters. The amplification of Raman signal using this design was recorded with enhancement factor of ∼108 for the most prominent Raman mode. The hotspots are uniformly distributed all over the surface. This ensures easy and quick detection of analytes with a high order of repeatability. The roughening of the surface was carried out under controlled environment which justifies reliability, reproducibility and high-fidelity of the proposed design/substrate. The proposed design can be fabricated easily and is very cost effective. This SERS substrates has the potential to measure up to picograms levels of compounds constituting nitro-based explosives which has been validated using analytes such as urea and p-nitrobenzoic acid (PNBA).