AC RESPONSE OF FRACTAL METAL ELECTROLYTE INTERFACES

The problem of the so-called constant phase angle (CPA) behaviour in the frequency-dependent impedance of an electrolyte in contact with a rough metallic electrode is studied by a numerical treatment and by real-space renormalization of two-dimensional electrical networks. Deterministic and disordered fractal boundaries based on quadratic Koch curves are considered. Both methods indicate that the CPA exponent eta can be estimated qualitatively from both the fractal dimension of the interface and from the scaling of the high-frequency response with system size.