Excitation transport in solution: A quantitative comparison between GAF theory and time-resolved fluorescence profiles

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Abstract
Time-correlated single photon counting was used to monitor fluorescence concentration depolarization for DODCI in glycerol. For DODCI concentrations below ∼10−3 M, the present experiments have minimized self-absorption and excitation trapping artifacts to the extent where they contribute negligibly to the observed differences between experimental fluorescence profiles and profiles computed from the Gochanour–Andersen–Fayer three-body theory for excitation transport in solution. The three-body theory accurately describes fluorescence depolarization at the lower dye concentrations. At higher concentrations, the measured decay in Gs(t), the probability that the excitation resides on the laser-excited molecule, is perceptibly slower than predicted by the three-body theory. This deviation may arise from nonrandom dye distributions in solution, rather than from errors in the three-body theory. The experimental decay is equally well described at all concentrations by an earlier analytic theory which was developed by Huber, Hamilton, and Barnett.