Abstract
An exact relation for the reactivity dependence of the recombination probability in the presence of a scavenger is derived. For a spherical symmetric system with a uniformly distributed scavenger this relation expresses the partially diffusion controlled recombination probability in terms of the totally diffusion controlled recombination probability. The relation is valid for a space‐dependent diffusion coefficient and for an arbitrary potential energy between the particles. The relation is proved only for a three‐dimensional system, but it appears to be valid also for one‐ and two‐dimensional systems.