The optical property and SERS of Ag sol adsorbed with different anions(CO32-, OH-, I-, Br-, Cl-) have been studied. It was found that the anions with higher nucleophilicity have stronger adsorption on the Ag particles accompanied by that a new absorption peak of Ag sol appeared at longer wavelength, which was caused by the reduction of the free electron d. in the surface layer of the Ag particles. The origin of SERS is attributed to the chemisorption of the anions on the Ag particles. Its intensity increases with increasing surface coverage of adsorption on the Ag particles.

Key words: PEPTIZATION, INFLUENCING FACTORS, SILVER, OPTICAL PROPERTIES, CHEMICAL ADSORPTION, ELECTRON DENSITY, SOL, SURFACE ENHANCED RAMAN SCATTERING, RAMAN SPECTROMETRY