Surface Raman scattering of methanol, 1-propanol, 1-pentanol, and 1-butanethiol on in situ and emersed silver electrodes

Surface Raman scattering is used to study the adsorption of several straight-chain alcohols (methanol, 1-propanol, 1-pentanol) and a straight-chain alkanethiol (1-butanethiol) at Ag electrodes. Surface-enhanced Raman scattering (SERS) studies are carried out on both in situ and emersed roughened electrodes. Normal surface Raman scattering is performed on mechanically polished, mirrored polycrystalline electrodes that have been emersed from solution. It is generally observed that the Raman scattering results, in terms of the orientation and bonding for the alcohols and the thiol, are similar on rough and mirrored electrodes. This observation suggests that SERS probes the average surface molecules in these cases and not only those existing at chemically distinct surface sites. The utility of emersed electrode approaches for molecular characterization of the electrochemical interface is demonstrated for these systems. The interfacial molecular structure for these in situ organic species appears to be maintained upon emersion.