SURFACE-ENHANCED RAMAN-SPECTROSCOPIC STUDY OF ISOMERIC ANISIDINES ADSORBED ON COLLOIDAL SILVER PARTICLES

Surface-enhanced Raman scattering (SERS) spectra of o-, m- and p-anisidine molecules were compared with the solution Raman spectra. The experimental results suggest that the o- and m-anisidine molecules are adsorbed on the metal surface principally through the nitrogen atom, whereas the p-anisidine molecules are adsorbed through the pi-system of the phenyl ring. This observation is explained in terms of the electron densities on the N and O atoms and in the phenyl ring as reflected by the Hammett sigma values of the isomers. Charge-transfer interactions have been shown to contribute significantly to SERS.