Partially diffusion-controlled reactions of isolated pairs in condensed media

A theory is formulated which, within the framework of the diffusion model, takes into account a reaction probability α (?1) of an isolated pair of reactants at the encounter separation. Re-encounters are envisioned in the liquid phase; however the resultant time-dependent reaction rate can be expressed mainly in terms of the first encounter probability. Other useful information, such as the ultimate escape probability, reaction with a uniformly distributed scavenger, etc., are obtained from the fundamental result, the last by using a Laplace transformation. Model calculations are provided and some actual cases are analyzed with a specific physical interpretation of α.