Abstract
AbstractTriplet → singlet energy transfer in nylon 66 film (donor) dyed with proflavine (acceptor) is demonstrated by a decrease of the nylon phosphoresence lifetime and an increase in the proflavine delayed fluorescence/nylon phosphoresence ratio with increasing proflavine concentration. Although the observed donor phosphorescence decay is apparently exponential, the transfer is probably via a long‐range dipole–dipole (Förster) interaction, rather than by triplet exciton migration. Arguments are advanced to support this view. Proflavine delayed fluorescence produced by a direct excitation process is also observed. The decay time for this process is roughly an order of magnitude less than that for the sensitized process. All emission intensities are shown to vary linearly with exciting light intensity. Finally, temperature dependence of proflavine delayed fluorescence under different excitation conditions is shown. The efficiency of direct excitation process increases markedly near −50°C as the temperature is increased; the sensitized delayed fluorescence intensity follows that of the nylon phosphorescence with increasing temperature, as expected.
Published Version
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