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.