Comparative study of surface-enhanced Raman scattering activities of three kinds of silver colloids when adding anions as aggregating agents

The surface enhanced Raman scattering (SERS) spectrum of methylene blue (MB) varies observably when using different kinds of silver colloids as SERS active substrates. The colloids were synthesized by three different methods. Sodium chloride, sodium sulfate, sodium nitrate were chosen as aggregating agents in this study. Three kinds of anions were performed on hydroxylamine-reduced silver colloid and the effect of the chloride anion was investigated in the three SERS-active colloids. From the results it can be concluded that the interaction between analyte and silver nanoparticles is different in different kinds of colloidal environments and the addition of anions also has a great influence on SERS spectrum. The effects on the SERS spectra were qualitatively explained through the study of SERS spectra for various silver colloids and aggregating agents in this paper.