SERS Investigation of Interfacial Methanol at Silver Electrodes*

Interfacial solvent structure at Ag electrodes in methanol electrolyte systems has been studied by using surface-enhanced Raman scattering (SERS). The potential dependence of the SERS response suggests that methanol interacts with Ag electrodes through the oxygen end of the molecule. At all potentials studied, the C-0 bond appears to remain largely parallel to the surface. It is proposed that at potentials positive of the PZC only one oxygen p-orbital is directed toward the Ag surface. Near the PZC, it is postulated that two methanol orientations are detected simultaneously in the presence of Li+. Evidence is presented for the influence of supporting electrolyte cation and anion on the orientation of methanol at these electrodes.