Energy quenching kinetics beyond the rate concept

The non-Markovian integro-differential kinetic theory of bimolecular transf er reactions in solutions is considered as well as a number of its applicat ions to the photo-induced multistage reactions of energy and electron trans fer. The theory valid in the lowest order approximation with respect to the concentration of reaction partners. It is known as integral encounter theo ry (IET) which uses integral terms instead of reaction rates and memory fun ctions as their kernels instead of time-dependent rate constants. The rever sible inter-molecular energy transfer and quenching by charge separation ar e considered more in detail as excellent examples of the processes whose co nventional rate description is impossible. A number of other applications o f IET are listed and briefly refereed. An important modification of the the ory extending its validity region for larger concentrations and longer time s is also reported. (C) 2001 Elsevier Science B.V. All rights reserved.