Surface-enhanced Raman scattering by composite structure of gold nanocube-PMMA-gold film

In this study, we experimentally prepared composite structures of 170 nm gold nanocube, poly(methyl methacrylate) (PMMA) spacer layers with different thicknesses, and 50 nm gold film as substrates for surface plasmons excitation and surface-enhanced Raman scattering (SERS). The SERS spectra of gold nanocube and the composite structure were studied by using a 633 nm laser as an excitation source and rhodamine 6G (R6G) as the Raman probe molecule with 5.625 µg/mL gold nanocube aqueous solution. It was found that the composite structures produced much stronger SERS signals than that with the single gold nanocube structure. The relationship between the intensities of SERS Raman peaks and the PMMA spacer layer thicknessess of the composite structures was found to have the same trend as that between the Raman enhancement factor and PMMA spacer layer thickness obtained by the finite element method simulation. Furthermore, a R6G concentration as low as 10−12 M could be detected by the composite structure.