Surface-enhanced Raman Scattering Activity Study of Molecule in Mixed Negatively and Positively Charged Silver Colloidal Solution

Both negatively and positively charged silver colloids were prepared in aqueous solution for surface-enhanced Raman scattering (SERS) by the reduction of silver nitrate with sodium citrate and hydrogen peroxide under basic condition, respectively. By means of transmission electron microscopy (TEM), the observation of morphologies of negatively charged silver colloid (NSC) and positively charged silver colloid (PSC) has been presented, and the aggregation behaviors of NSC and PSC as well as the mixture of NSC and PSC induced by the addition of fuchsine basic molecules examined. SERS from fuchsine basic molecules in above mentioned colloidal systems were recorded respectively and compared with each other. The results show that the mixture of NSC and PSC could form the aggregation morphology different from that of single NSC and PSC and bring about the favorable effect on SERS behavior for the adsorbed fuchsine basic.