Adsorption of dicarboxylic acids onto nano-structured silver surfaces – surface-enhanced Raman scattering studies of pH-dependent adsorption geometries

Understanding and shaping adsorption orientations of molecular compounds on nano-structured metallic surfaces is an important issue across many areas of contemporary research including the design of nano-structured surfaces and catalytic processes. Here, we used surface-enhanced Raman spectroscopy to study these orientations on nano-structured silver surfaces using dicarboxylic acids (maleic acid and fumaric acid) as model substances. Results revealed a clear pH dependence of the observed adsorption geometries of dicarboxylic acids correlating well with the dissociation states of the two acidic groups. Our data demonstrate the potential of the technique and contribute to an improved understanding of adsorption orientations of molecules at the interface between nano-structured metal surfaces and a liquid phase