SPECIAL FACETS OF DIFFUSION AND ENERGY-TRANSFER IN MACROMOLECULAR SYSTEMS

We consider energy transfer in polymers in dilute solutions and model it as a purely incoherent, hopping exciton motion which ends at perman ent traps, whose positions along the polymer chain are fixed. The tran sport involves not only steps along the chain but also steps between s ites which are far away along the chain's backbone but near to each ot her in Euclidean space. This possibility leads to very peculiar featur es of the excitation's diffusion along the chain, due to strong correl ations between subsequent steps. The process depends strongly on wheth er the chain is frozen or moves. We show that conformational changes i nfluence trapping strongly, even if they are relatively slow on the ti me scale of the hopping motion.