Surface Enhanced Raman Scattering of Imidazole adsorbed onto Silver Colloidal Particles

Abstract

SER spectra of imidazole adsorbed on silver sols have been investigated and compared with the Raman spectra of the neutral molecule and of the conjugated acid and base in aqueous solutions. Two different orientations of the adsorbate onto silver colloidal particles have been identified, depending on the adsorbate concentration and the presence of chloride anions in the colloidal dispersions. A face-on orientation of imidazole respect to the silver surface is favoured by the adsorbate dilution, whereas an edge-on orientation of the imidazolate anion is induced by addition of a small amount of NaCl.