Study of interaction between aspartic acid and silver by surface-enhanced Raman scattering on H2O and D2O sols

Three different surface-enhanced Raman scattering (SERS) spectra are record ed for aspartic acid on H2O silver sols under different concentrations and pH values. The analysis of the results shows that it interacts with the met al surface in its dianionic form in two different ways, depending on the pH and concentration. Moreover, in some cases the fumarate anion is detected, which results from the chemical surface transformation of the aspartate. T he N-deuterated aspartic acid adsorbed on the D2O silver sols gives rise to only one SERS spectrum as a consequence of the interaction of amino and ca rboxylate functional groups of the dianion with the metal, independent of t he concentration and pD. (C) 2001 John Wiley & Sons, Inc.