Diffusion impedance — An extended general analysis

Abstract The finite diffusion impedance is analysed using a diffusion factor K, where K=δ(2/D)1/2. The solution for a single electroactive species shows the indepedence of the frequency distribution to the other electrode coefficients. Of greater interest is the effect of two separate electroactive species, each with different diffusion coefficients, since they can give rise to a depression of the complex plane plot. The analysis also suggests that changes in film thickness may be monitored in situ by impedance measurements.