Anomalous observations in d.c.-polarized transient conductivity measurements in aqueous solutions due to electrode surface effects

Abstract

Transient conductance changes in aqueous solutions following a short pulse of radiation are almost universally performed using conductivity cells where chemically inert electrodes are in contact with the solution. The changes which are measured are usually small compared to the background conductance arising from the polar nature of the solvent and the presence of ionic solutes. This large background current may cause field distortions near the surfaces of the electrodes. These distortions may cause the resultant transient measurements to be incorrect, reflecting neither the magnitude nor the kinetics of the unperturbed radiation-induced conductance changes. The cause of these errors is discussed and representative observations are presented. A simple method of minimising and eliminating such errors is presented with the aim of improving the reliability and calibration accuracy of pulse-radiolysis conductivity installations.