Richard H. Henze

Transient-current characteristics of dispersed charges in a non-polar medium

— Transient currents of reverse micelles in a non-polar solvent from voltage step stimuli were studied to investigate the electrophoretic behavior of the charges. The current showed a sharp peak directly after the voltage application and decayed afterward while it exhibited various time-dependent transients depending on the applied voltage and the charge content after the bias was removed. A one-dimensional drift-diffusion model could reproduce the behaviors for various conditions. The forward transient could be well-explained by a simple capacitor-charging model with a limited charge. It turned out that the broad peak in the reverse transient current is formed by a competition between an increasing number of charges available for drift and a decreasing electric field resulting from mixing of opposite charges and that the full development of the peak is a good indication of complete polarization of the charges. The slow initial release of charges from the electrodes is due to the electric field developed by accumulated charges that decreases as the charges are released by diffusion. The high density compaction of charges against the electrodes reduces electric-field screening by the accumulated charges and enables more accumulation, but individual charge-to-charge interaction limits the density.