Exciton Dynamics in thin wires

Abstract

When are molecular wires thin enough to show one-dimensional exciton kinetics? What are the characteristics of one-dimensional kinetics? What applications are there? Cylindrical naphthalene wires (5-5000 nanometer radius) show a definite one-to three-dimensional transition (about 25 nm for triplet excitons at 4 K; 40 nm at 77k). Nuclear channel pore membranes (polycarbonate) serve as templates and calibrators. Monte Carlo simulations on finite-width wires are consistent with the experiments. Vycor glass pores are effectively one-dimensional. A new experimental criterion is based on excitation pulse width. It gives both topological and stochastic information (i.e. dimensionality and hopping rate). Its applicability to ultrathin wires and porous glass is demonstrated via simulations and experiments. The triplet exciton migrat (multiple hopping) length is 50-2-100 molecules for all samples.