Dispersive recombination in condensed phases

Two interpretations of the parameter α are presented for a second-order equal-concentration kinetic equation with time-dependent reaction rate coefficient k(t) ∝t^α-1, 0<α≤1. The first, valid for any system, is in terms of the activation energy distribu for recombination and follows from the time dependence of the activation energy implied by the form of k(t). The second, valid for systems in which the time dependence of k(t) results from a distribution of reaction rates, is analogous to the interpretation of stretched exponentials as a superposition of exponential decays.