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 π‐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 σ values of the isomers. Charge‐transfer interactions have been shown to contribute significantly to SERS.