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Raman spectra of pyridine-2,6-$d2$, pyridine-3,5-$d2$, pyridine-4-d and pyridine in aqueous sodium borohydride generated silver sols display time evolving multiplicity of $A1$ surface enhanced Raman scattering (SERS) active bands. Addition of gelatine, polyvinyl alcohol or agar agar alters the intensity characteristics of some components of each SERS active vibration, allowing identification of bands in pyridine adsorbed onto different crystal faces of the metallic silver substrate. The isotopic data allow investigation of alterations of the molecular force field induced by adsorption onto different sites.