Reflectance and ellipsometric study of anodic film on platinum electrode

The anodic films on platinum electrode in 0.05 M sulfuric acid solution were examined by means of ellipsometry. By measuring the relative phase retardation (Δ), relative amplitude reduction (tanψ) and also the intensity of the reflected polarized light, the optical constants of the films (n, k) and thickness (τ) at various potentials were obtained. The results showed that the optical properties of the film remain nearly constant (n = 2.8, k = 1.7) while the thickness increases from 2 Å to 5 Å with anodic potential. From this evidence, it is concluded that the film is made of an oxide of platinum forming a definite phase.