Voltammetry using an electrode surface continuously renewed by laser ablation and its demonstration on electro-oxidation of L-ascorbic acid

A new type of voltammetry, called laser ablation voltammetry (LAV), is demonstrated by measuring voltammograms for electro-oxidation of ascorbic acid (AA) as a model reaction which is sensitive to the condition of an electrode surface. In LAV, the electrode surface is irradiated with a laser pulse at constant intervals of a few seconds during the potential scan. Because the ablation action of the laser pulse can renew not only the electrode surface but also the electric double layer and the diffusion layer at the same time, LAV gives steady-state voltammograms under a constant condition of the electrode surface without using any forced mass transfer such as rotation of the electrode. The voltammogram exhibits a large and periodic current fluctuation concomitant with each laser pulse and thereby its shape is similar to that of the polarogram obtained with a dropping mercury electrode (DME). Because of these features of LAV, steady-state voltammograms could be obtained reproducibly even for the electro-oxidation of AA with a gold electrode without special pretreatment. Further, taking into account the similarity between LAV and polarography, the pH dependence of the half-wave potential was examined by LAV. Comparison of the pH dependence obtained in this work and reported in the literature gave fair agreement. This fact has proved that LAV is a promising voltammetric technique which is readily applicable even to voltammetric studies of electrode reactions which foul the electrode surface. (C) 1999 Elsevier Science S.A. All rights reserved.