Analysis of the visible absorption and SERS excitation spectra of silver sols

Abstract

The absorption spectra of silver sols in various stages of particle aggregation, as well as the surface-enhanced Raman scattering (SERS) excitation of citrate adsorbed on the colloid particles have been deconvoluted into a set of Gaussian bands. The absorption wavelength variation upon aggregation of the silver sols can be satisfactorily explained using an exciton model and a linear arrangement of the aggregated silver particles. Evidence is presented which shows SERS is only observed from excitation into the absorption bands associated with the aggregated colloid particles. A linear relationship was found to exist between the intensities of the aggregate absorption band and the SERS signal...