Study of SERS efficiency of metallic colloidal systems

The aim of this work was to determine the influence of colloidal silver and gold nanoparticles on the intensity of Raman scattering observed for analytes dissolved in the water. The testing analytes were rhodamine B and rhodamine 6G. A special emphasis was placed on the choice of optimal method of preparation of colloids and also on the determination of the influence of the aggregation environment on surface-enhanced Raman scattering (SERS) efficiency and stability of colloids. Potassium chloride, sodium chloride and hydrochloric acid are used as aggregating agents. Simply Raman spectrometer and UV-Vis spectrophotometer were used for measurements. The total intensity of inelastic scattering on molecules exhibited up to 106-108fold increase in the presence of metallic nanoparticles with a detection limit of analyles being shifted up to the nanomolar concentration. It was observed that SERS enhancement factor varies strongly depending on kind and concentration of used aggregating agent (especially on the concentration of Cl−ions). These changes in SERS efficiency of colloid were reflected through changes on the absorption spectra.