Surface-Enhanced Raman Scattering Studies on Aggregated Gold Nanorods

Abstract

Surface-enhanced Raman scattering (SERS) of adsorbed molecules on gold nanorods (NRs) with dimensions of 10 nm × 27 nm was studied on silica surface with low to high surface coverage of NRs. The study was carried out to investigate both the dependence of the SERS intensity on the number of NRs and the NRs spacing on the silica surface. SERS of adsorbed molecules such as 2-aminothiophenol (2-ATP) and the capping molecules (hexadecyltrimethylammonium bromide) was studied on these surfaces using a near-IR laser excitation source (1064 nm). To produce silica surfaces covered with NRs, two approaches were used. In the first approach, monodispersed NRs gradually deposited from solution to silica surface and their number was increased by increasing the deposition time. In the second one, the NRs were first aggregated in solution and then deposited on the surface. Although using the first approach it was possible to prepare surfaces with high NR surface coverage, SERS intensity was found to be stronger for adsorb...