Energy Transfer Mechanisms and the Molecular Exciton Model for Molecular Aggregates1, 2

Energytransferphenomenacontinuetofascinatethebiologist, chemist, and physicist, and the literature contains numerous experiments designed to demonstrate the presence of excitation energy transfer. At the present stage of development of the theoryofsuchprocesses, thegoal oftheseresearchesmightwell be not merely the demonstration of the presence of energy transfer, but a more detailed investigation designed to establish which available mechanism of energy transfer is operative. The field of excitation energy transfer is replete with redundant and overlapping terms, whose multitude itself lends little order to the subject. Various authors quote, as energy transfer mechanisms, exciton transfer, resonance transfer, dipole-dipole transfer, inductive resonance, resonance force transfer, virtual photons, and diffuse excitation, among others. This paper will be devoted to the laying down of a further perspective for the discrimination and understanding of the main types of excitation energy transfer. A necessary