Abstract
A newly developed electrochemically plated Ag electrode was used to study the surface-enhanced Raman scattering from pyridine adsorbed on the electrode. It was found that in basic and neutral solution, the adsorbed species on the electrode is pyridine. In acidic solution without chloride ion, the pyridinium ion turns to pyridine on the electrode. However, in an acidic solution with chloride ion both pyridinium and chloride ions are adsorbed together on the Ag electrode and pyridinium chloride forms, then the 1026-cm −1 Raman band appears for the v 8 mode. At a potential of −0.45 V (SCE), chloride ion is driven away from the electrode and pyridinium ion decomposes immediately into pyridine. This potential is called the “driving-off potential”. The effects of bromide and iodide ions were also studied. A model is proposed for the behavior of pyridine, pyridinium ion, and pyridinium chloride on the Ag electrode with and without applied potential. © 1984, American Chemical Society. All rights reserved.