SILAR grown Ag nanoparticles as an efficient large area SERS substrate

Ag nanoparticles having different size and coverage are grown on large area glass substrate (similar to 10cm(2)) using low cost successive ionic layer adsorption and reduction (SILAR) method. The SILAR parameters, such as reduction time and growth cycles are optimized to grow Ag nanoparticles with appropriate size and coverage showing maximum surface enhanced Raman scattering (SERS) enhancement of Rhodamine 6G(R6G). For fixed growth cycles, the size and the coverage of the grown Ag nanoparticles are found to increase with the reduction time and then saturate. The size and coverage of the grown Ag nanoparticles monotonically increase with growth cycles. However, for higher growth cycles, the shape of Ag nanoparticles could not maintain their sphericity and became rock shaped/nonspherical particles, giving rise to intense quadruple plasmon resonance. The growth mechanism is proposed. Further, SERS activity of the grown Ag nanoparticles is studied for an industrial pollutant methylene blue (MB). The observed SERS enhancement factor (similar to 10(9)) for MB is much higher than the reported values in literature. Measured relative standard deviations values of Ag nanoparticles grown with optimum SILAR parameters suggest the excellent homogeneity and reproducibility of the SERS signal.