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 PbII 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.