Intermolecular energy transfer: Retardation effects

An extension of previous theoretical work on the unified theory of radiative and radiationless intermolecular energy transfer is presented. A generalized transfer rate accounting for molecular vibronic structure is derived, enabling the formal connection with the classical Förster formula to be fully established. The solution to an apparent paradox concerning the long‐range R−2 dependence of the intermolecular energy transfer rate is demonstrated. It is shown that the inverse square behavior should be modified by inclusion of an exponential factor due to the presence of other acceptors. A corrected Förster decay rate including an R−4 contribution, in addition to the conventional R−6 term, is obtained and the means of characterizing distinctive features of the unified approach are discussed with reference to some model systems. Finally the relation between retardation and quantum uncertainty effects in molecular energy transfer are considered.