Energy Transfer in Solid Solutions and on Fractal Polymer Surfaces

Abstract

The electronic energy transfer from rhodamine B to several acceptor dyes in cellulose nitrate solid solution and on the surface of membrane filters of the same polymer has been investigated at room temperature. In polymer matrix the Forster theory has been confirmed and critical distances Ro have been calculated from the theoretical equation and have also been determined by energy transfer experiments measuring the fluorescence decay time of the donor. Applying new fractal concepts to energy transfer in porous membranes, the fractal dimension of the polymer surface has been determined under several conditions. The values agree with others obtained by adsorption experiments.

A fluorescence lifetime sensor for Cu(I) ions

“…If the diffusional displacement of the donor or acceptor molecule during the donor lifetime is comparable to the critical transfer distance R 0 , the diffusion may markedly influence the donor decay. For the simplest case of the lack of diffusion, a very low donor concentration (i.e., energy migration may be neglected) and a homogeneous distribution of acceptors around the donor, the Förster model applies, giving a well known formula for the fluorescence decay [14][15][16]:…”

Triplet Energy Migration among Energetically Disordered Chromophores in Polymer Matrixes. 2. Thermally Induced Supertrap Formation

“…Many workers have proposed models to describe the complicated relaxation process of excited states. − Transport properties in inhomogeneous systems are described by a distribution of microscopic (site-to-site) transfer rates (temporal disorder) and by dispersive magnitudes of interactions with the surroundings (energetic disorder). Spatial randomness may be modeled by fractals, , and temporal disorder can be accounted for by using a waiting-time distribution, as in continuous-time random walk (CTRW), , and multiple trapping (MT) , approaches.…”

Triplet Energy Migration among Energetically Disordered Chromophores in Polymer Matrixes. 1. Monte Carlo Simulation for the Hopping of Triplet Excitons

“…Many workers have proposed models to describe the complicated relaxation process of excited states. − Transport properties in inhomogeneous systems are described by a distribution of microscopic (site-to-site) transfer rates (temporal disorder) and by dispersive magnitudes of interactions with the surroundings (energetic disorder). Treatment of the full microscopic problem is an arduous task, which calls for extensive numerical simulations.…”