Adsorption of urea on Au(100) and Au(111) electrode surfaces studied by in-situ Fourier-transform infra-red spectroscopy

The adsorption of urea on Au(100) and Au(111) electrode surfaces was studie d through a combination of cyclic voltammetry and Fourier-transform infra-r ed spectroscopy. The infra-red spectra indicate that urea molecule is adsor bed on Au(100) with a molecular plane normal to the electrode surface. On A u(111), urea showed a different coordination. Lifting from 5x20 to 1x1 on t he Au(100) surface was accelerated by the adsorption of urea. The kinetics of the 5 x 20 to 1 x 1 transition was monitored by a time-resolved IRAS mea surement. The lifting of a reconstructed 5 x 20 surface to 1 x 1 proceeded within 20 s. However, the reconstruction from the 1 x 1 to 5 x 20 surface, required a longer period of time, more than 70 s. (C) 1999 Published by Els evier Science B.V. All rights reserved.