Abstract: Characteristics and change rule of an electrode process can be reflected by in-situ graze ellipsometric parameters. The mathematical and physical model of the graze ellipsometry has been put forward by combining the model of diffusion layer in electrochemical reaction with graze ellipsometry experiments. The physicochemical meaning of ellipsometry parameters Δ and Ψ has been explained. The diffusion layer near the electrode is equivalent to a phase retarder and an amplitude absorber. The influence of the concentration of electroactive substance and diameter of spot of the incidence light on Δ and Ψ is discussed with reference to experiment results.

Key words: Graze ellipsometry, Electrochemical reaction, Diffusion layer, Phase retarding, Amplitude absorbing