INFLUENCE OF FRACTAL GEOMETRY ON GEMINATE ESCAPE PROBABILITY, MEAN RECOMBINATION TIME, AND HOMOGENEOUS REACTION-RATE

The effects of fractal geometry on the geminate escape probability, the mean recombination time, and the homogeneous reaction rate have been evaluated for both neutral and ionic recombinations. Following López-Quintella et al. [J. Chem. Phys. 88, 7478 (1988)] the fractal geometry effect is exhibited through a position-dependent diffusion coefficient. In general, the mean recombination time increases with the mean free path, even more significantly when the latter is comparable with the reaction radius or greater. The escape probability increases with the mean free path for nearly diffusion-controlled reactions but decreases with it for reactions that are governed by energy-loss considerations. The homogeneous ionic recombination rate decreases with the mean free path, in approximate agreement with the Monte Carlo results of Tachiya [J. Chem. Phys. 87, 4108 (1987)] if the scale parameter is taken to be 3.7 times the mean free path. © 1990 American Institute of Physics.