Electric field suppression of hopping charge recombination

The theory of hopping reactions between charged particles in high-mobility non-polar liquids is essentially extended to account for the electric field effect on a bulk electron-ion recombination. It turns out that the rate constant of the hopping recombination decreases with the electric field contrary to what was obtained for diffusional recombination. Such a difference may serve for experimental discrimination between hopping and diffusional reaction mechanisms. Their interrelation is traced within a more general Torrey's model of a solvated electron random walk with an arbitrary step length determined by the free electron diffusion. The coefficient of linear field dependence obtained for low fields in the contact approximation changes the sign in passing from a short mean step length (diffusional recombination) to a much larger mean step length (hopping recombination). (C) 1997 American Institute of Physics. [S0021-9606(97)50840-3].