Heat-induced morphological control of gold nanoparticle films for surface-enhanced Raman scattering (SERS) measurements

Gold nanosphere (NS) films with different morphologies were prepared on glass substrates, by salting-out the colloidal solution with NaOH or NaClO4, and subsequent annealing at 100–150 °C. Surface-enhanced Raman scattering (SERS) spectra of rhodamine 6G (R6G) were measured by casting the R6G solution or by dipping into the R6G solution. Annealing at elevated temperatures certainly enhanced the SERS signal, though the optimum annealing temperature was different with the initial morphology of the NS film. The NS film prepared from NaClO4 and annealed at 100 °C gave the largest SERS signal in this study.