Interpretation of AC surface current density by deconvolution of potential differences in solution

Abstract

In localized electrochemical impedance techniques, the measurable AC potential difference in solution is related to the AC surface current distribution simply by using Ohm’s law. However, this relationship is not true for the cases in which current distribution is non-uniform. In order to correctly obtain the surface current density, deconvolutions of the solution potential difference using the base line stripping procedure and the Fast Fourier Transform method have been simulated and discussed. A more accurate spatial estimate of the surface current density distribution can be obtained by deconvoluting the measured potential difference distribution in the solution than by simply using Ohm’s law. The accuracy of the deconvolution using the base line stripping procedure is greatly dependent on the errors of measurement, and experimental data with a very low noise level are therefore required. Deconvolution by a Fast Fourier Transform is also very sensitive to noise and discontinuity in the potential difference distribution, but the sensitivity can be dramatically reduced to an acceptable level by using a low pass filter.