ON THE DISSOLUTION KINETICS OF 2-DIMENSIONAL URIDINE LAYERS ADSORBED ON GOLD SINGLE-CRYSTAL ELECTRODES

The kinetics of dissolution of a two-dimensional chemisorbed layer mad e of uridine molecules adsorbed onto gold single-crystal electrodes ha ve been studied by the potential step technique. Current transients ha ve been recorded after single potential steps aimed at triggering the dissolution of the uridine chemisorbed monolayer formed on Au(111), Au (13,13,12) and Au(554). Irrespective of the electrode surface all the transients have satisfactorily been described by a model that combines a desorption step with a simultaneous hole nucleation and growth proc ess. On the basis of a model considering an exponential law of nucleat ion and a surface diffusion-controlled growth, it is found that an inc rease of the step density of the electrode surface by affecting the or dering of the organic layer enhances markedly the rate of formation of holes in the film but slows down the expansion of the holes. The infl uence of the temperature and of the surfactant concentration on the nu cleation and growth parameters is also reported. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.