Electrochemical and Raman spectroscopic studies of pyrazine adsorption at the Au(210) electrode surface

Abstract

Chronocoulometry and Raman spectroscopy have been applied to study pyrazine adsorption at the Au(210) electrode surface. The adsorption isotherms, Gibbs energies of adsorption, and the electrosorption valency for pyrazine adsorption at the Au(210) electrode surface have been determined. Surface-enhanced Raman Scattering (SERS) spectra of pyrazine adsorbed on an "unroughened" Au(210) electrode surface have been obtained for the first time. The thermodynamic data and the SERS spectra indicate that pyrazine adsorbs on the Au(210) electrode via the nitrogen lone pair (N-bonded configuration) over the whole range of electrode potentials investigated. Consequently, the pyrazine molecule assumes only the vertical orientation at this surface of gold. The adsorption of pyrazine at the Au(210) and Au(111) surfaces is compared and the influence of the surface crystallography on the adsorption of this molecule at gold electrodes is discussed. Keywords: adsorption at Au(210), pyrazine, SERS, chronocoulometry.