ADSORPTION OF XYLENE-ALPHA,ALPHA'-DITHIOL ON SILVER INVESTIGATED BY RAMAN-SPECTROSCOPY

Ortho, meta, and para isomers of xylene-alpha,alpha'-dithiol (XDT) adsorbed on silver sol surfaces were investigated by means of surface-enhanced Raman scattering. Three isomers have been found altogether to be bound to silver via two sulfur atoms after losing their thiol protons. For o-and p-XDT, ring-surface pi overlap appeared also to occur albeit not so much substantially as S-Ag interaction. The benzene ring in the ortho and para isomers seemed thus to lie parallel, but that of the meta isomer to stand perpendicular to silver surface. Adsorbate orientations inferred from band frequency shift and band broadening looked consistent with those deduced from the electromagnetic surface selection rule.