Short range caging effects for reactions in solution. II. Escape probability and time dependent reactivity

Short range caging effects arising from the potential of mean force and a spatial dependence of the relative diffusion coefficient are examined for three probes of solution reactions. The escape probability that potentially reactive molecules escape each other rather than react is found to be depressed at small initial separations and enhanced at large initial separations when compared to predictions of a continuum diffusion description. Two measures of time dependent reactivity, namely the ’’time dependent rate constant’’ and the probability that initially separated members of amolecular pair remain unreacted at time t, are found to exhibit nonnegligible short range effects which can be interpreted in terms of ’’caging.’’