AC RESPONSE OF FRACTAL METAL ELECTROLYTE INTERFACES

The problem of the so-called constant phase angle (CPA) behaviour in t he frequency-dependent impedance of an electrolyte in contact with a r ough metallic electrode is studied by a numerical treatment and by rea l-space renormalization of two-dimensional electrical networks. Determ inistic and disordered fractal boundaries based on quadratic Koch curv es are considered. Both methods indicate that the CPA exponent eta can be estimated qualitatively from both the fractal dimension of the int erface and from the scaling of the high-frequency response with system size.