Surface Raman scattering of interfaces at Ag electrodes emersed from dimethylsulfoxide: spectroscopic evidence for an emersion-induced potential shift

Surface Raman scattering has been used to study AE electrodes emersed from LiBr solutions of dimethylsulfoxide (DMSO)although spectral evidence for an emersion-induced potential shift Interfacial DMSO structure Is generally s imilar to that in-situ, Is observed. The DMSO orientation at Ag electrodes is driven by interaction of the oxygen atom at potentials positive of the p otential of zero charge (pzc) and the sulfur atom at potentials negative of the pzc. Pronounced restructuring of DMSO occurs in the vicinity of the pz c. Specific Interactions between DMSO and electrolyte ions are clearly dete cted in the emersed interface. The observed potential shift is attributed t o reorientation of the DMSO solvent dipoles at the emersed layer gas interf ace. These results represent the first spectroscopic evidence for the exist ence of an emersion-induced potential shift. (C) 1999 Elsevier Science All rights reserved.