Surface-enhanced resonance Raman spectroscopic studies of the PbII complex of 1-(2-pyridylazo)-2-naphthol adsorbed on Ag Sol

Abstract

The resonance Raman (RR) and surface-enhanced resonance Raman (SERRS) spectra of the Pb^II complex of 1-(2-pyridylazo)-2-naphthol, Pb(PAN)₂, are reported and assigned, and the nature of the adsorbed species determined. There is clear evidence for chemisorption of Pb(PAN₂) on silver, which gives rise to substantial alteration of the Raman spectrum. Comparison of the variation of Raman intensities with excitation wavelengths for the RR and SERRS spectra indicates that there is a contribution to the surface-enhancement from both the chemical and electromagnetic SERS mechanisms. The dependence of the Raman spectrum on Pb(PAN)₂ concentration and co-adsorbed Cl^– is investigated. There is a linear relationship between adsorbate concentration and SERRS intensity, enabling the technique to be used for the quantitative determination of Pb(PAN)₂ down to ca. 1 ppb.