RECOVERY OF ACCEPTOR CONCENTRATION DISTRIBUTION IN A DIRECT ENERGY-TRANSFER EXPERIMENT

The Klafter-Blumen equation, describing the kinetics of direct non-rad iative energy transfer (DET) by the Forster mechanism, is extended to the case of guest molecules distributed non-uniformly in a space of kn own dimensionality. We describe a technique to recover the distributio n of acceptor molecules in the medium, based upon the theory of the Fr edholm integral equation of the first kind and its numerical solutions . The technique has been tested by computer simulations, and applied t o several sets of experimental data. Examples are chosen from experime nts involving energy transfer between dyes absorbed to the surface of polymeric microspheres, between dyes attached to polymer chains diffus ing across an interface, and between dyes which undergo particle aggre gation when dissolved at high concentrations in polymer matrices. Base d on a comparison of these results with those obtained from directly f itting donor fluorescence decay profiles to the Klafter-Blumen equatio n, the merit of this new approach and its limitation are discussed.