AN EXAMINATION OF THE RELATIONSHIP BETWEEN SURFACE ENHANCED RAMAN-SCATTERING (SERS) INTENSITIES AND SURFACE CONCENTRATION FOR PYRIDINE ADSORBED AT THE POLYCRYSTALLINE GOLD AQUEOUS-SOLUTION INTERFACE

Surface enhanced Raman scattering (SERS) data are presented for pyridine adsorbed onto both smooth and roughened polycrystalline gold electrode surfaces. It was found that, for smooth surfaces, time independent (stable to within 10% of the initial value) intensities of the totally symmetric ring breathing mode of pyridine (1010 cm-1 band) could be measured by applying slow oxidation-reduction cycles between each intensity measurement. The potential and concentration dependence of the intensity of the 1010 cm-1 band was therefore determined. Independently, the isotherms for pyridine adsorption at smooth polycrystalline gold surfaces were obtained using chronocoulometry. The SERS data are compared to the surface concentration data. The SERS intensities are directly proportional to surface concentration at low coverages and deviate, becoming inverse, above half coverage concentrations. Lastly, the effect of surface roughness on the potential and concentration dependence of pyridine SERS was studied. No correlation between the SERS data from rough electrode surfaces and adsorption isotherms determined at a smooth surface was found.