The analysis of surface processes on solid electrons by combined modulated ellipsometric and reflectometric experiments

The response of reflectometric and ellipsometric parameters to small changes in the properties of the metal-solution interphase is analysed by the use of linear approximation expressions. It is shown that the changes in R₆ and R_⊥ are generally closely related, and the ratio (δR/R_⊥ /δR/R_⊥∥ may be insensitive to the value of n?_film. On the other hand, the ratio δΔ/(δR/R_⊥)₆ is shown to have always good sensitivity to ^n?film. For two surface processes on solid electrodes, gold surface oxidation and hydrogen adsorption on platinum, it is demonstrated that the information extracted from the combined measurements of Δ and R transients is more detailed and informative compared with the evidence obtained by reflectometry alone. A fast component is resolved in the process of gold surface oxidation, and shown to result optically in an apparent metallic film, which probably reflects changes in the properties and structure of the metal surface atoms induced as the oxygen uptake commences.