INVESTIGATION OF THE LONG-RANGE INHOMOGENEITY OF ADSORPTION LAYERS BY THE ELECTROSCATTERING OF LIGHT - ADSORPTION OF HYDROGEN AND ANIONS ON A PLATINUM-ELECTRODE

A theoretical study of diffuse scattering of light on a rough adsorbate-covered metal electrode surface has been given. Three different mechanisms of electroscattering (ES) signal formation have been described. Measurements of ES and electroreflection (ER) signals have been carried out on polycrystalline Pt in aqueous acid solutions in the potential regions in which hydrogen and anion (Cl- and Br-) adsorption takes place. It has been found that the ES and ER signals change when the surface morphology is changed by fast potential cycling. Comparison of the experimental values of the optical signals with theoretical estimations shows the existence of domain structures of the adsorbates investigated. For strongly-bound hydrogen at surface coverages of about 0.20-0.25 a good correlation of the adsorption layer and the inherent inhomogeneties is found. © 1990.