A diffusional alternative to the Marcus free energy gap law

Abstract

The results of the precise kinetic fitting of the highly exergonic electron transfer from excited perylene to tetracyanoethylene in acetonitrile were used to estimate the Stern–Volmer constant of perylene quenching by double channel electron transfer (to the ground and excited states of the radical ion pair). It appears that the Stern–Volmer constant is exactly the same as the diffusional height of the Rehm–Weller plateau, substituting the exergonic wing of the Marcus free energy gap law. Even the single channel transfer is shown to be fast enough that the quenching should be under true diffusional control at the highest available exergonicity.