Surface-enhanced Raman scattering of D-penicillamine on silver colloids

The Raman spectra of D-penicillamine in H2O and D2O were recorded under different acidity conditions, together with the respective SERS spectra on silver colloids. Vibrational assignments of the spectra obtained are proposed. The analysis of the SERS spectra shows that two of the conformers of D-penicillamine are adsorbed at least in their dianionic forms, and a stable chemical bond is established between the sulfur atom and silver. Additionally, carboxylate and amino groups also interact with the metal. The pK(a2) and pK(a3) apparent values are decreased upon adsorption. Copyright (C) 2004 John Wiley Sons, Ltd.