In situ infrared study of cytosine adsorption on gold electrodes

The adsorption of cytosine on an An electrode from 0.1 M NaCIO4 and HClO4 a queous solutions has been investigated by in situ surface-enhanced infrared absorption spectroscopy and cyclic voltammetry. Two different spectra were obtained at potentials below and above 0.1 V versus SCE in the NaClO4 solu tions. Similar behavior was observed also at 0.3 V versus SCE in the HClO4 solutions. From the spectral analysis, it was found that cytosine is physis orbed at negative potentials and is chemisorbed at positive potentials. Bot h the physisorbed and chemisorbed molecules are oriented with the N(3), C=O , and NH2 moieties directed towards the surface. A pair of redox peaks obse rved in the cyclic voltammogram were ascribed to the transformation between the physisorbed and chemisorbed states. (C) 1999 Elsevier Science S.A. All rights reserved.