NMR IMAGING OF THE TIME EVOLUTION OF ELECTROOSMOTIC FLOW IN A CAPILLARY

Velocity distributions in a capillary have been measured using NMR microimaging techniques, following application of pulsed electric fields in a weak ionic solution. The closed system exhibits electroosmosis in which the net fluid flow is zero. The time evolution of the electroosmotic flow profiles have been compared with the predictions of a theoretical model based on a wall slip within the Debye layer and drag of the remaining fluid. Excellent agreement is found both for the velocity distributions and for the time dependence of those distributions.