The dependence of the intensity of Raman bands of pyridine at a silver electrode on the wavelength of excitation

On increasing the wavelength of excitation over the range 350–700 nm, Raman bands of pyridine adsorbed at a roughened silver electrode are found to increase in intensity, relative to bands of the bulk medium (aqueous perchlorate or liquid pyridine) in contact with the electrode. The increase is observed in the bands at 1000–1050 cm^?1 and 1600 cm^?1 due to ring stretching, and similar increases are observed in other bands of the surface species, notably those due to CH stretching (3076 cm^?1), b₂ ring deformation (669 cm^?1, and AgN stretching (239 cm^?1, which have not been reported previously.