ADSORPTION AND PHASE-FORMATION OF URACIL DERIVATIVES ON GOLD AND SILVER SINGLE-CRYSTAL ELECTRODES

The adsorption of uracil, 6-methyluracil, 5-methyluracil (thymine) and 5,6-dimethyluracil from aqueous solutions on Au(lll) and Ag(lll) has been investigated by cyclic voltammetry, capacity measurements and cur rent transients, to elucidate the role of the electrode surface and of the intermolecular forces in the formation of ordered adlayers. From the calculated free adsorption enthalpies stability sequences for the condensed physisorbed phase were established. Our data show that the p roperties of the physisorbed adlayer are strongly influenced by the in termolecular forces, whereas in the chemisorbed state the influence of the substrate becomes dominant. For the chemisorbed molecules on Au(l ll) electrosorption valencies were estimated, which indicate an apprec iable charge transfer.