SERS INVESTIGATION OF THE COADSORPTION OF NICOTINIC-ACID AND 3-ACETYLPYRIDINE ON SILVER ELECTRODES

The pH-dependent solution Raman spectra of nicotinic acid and 3-acetylpyridine are reported in the wavenumber range 500-1750 cm-1. The changes with pH in the spectra of both molecules were correlated with the structure of the predominant solution species. Band assignments were carried out by referring to the spectra of the pure compounds and of related molecules. The surface-enhanced Raman spectra of nicotinic acid and 3-acetylpyridine co-adsorbed on polycrystalline silver electrodes were measured as a function of applied potential. The surface-active species were identified according to the solution and surface Raman shifts of the individual components. A surface configuration involving the interaction of nicotinic acid and 3-acetylpyridine is proposed to explain the observed spectra.