Diffusion of Triplet Excitons in Pure Crystalline Naphthalene

The diffusion of triplet excitons in pure crystalline naphthalene is investigated using delayed fluorescence, arising from the annihilation of two triplet excitons producing a fluorescing singlet exciton, as a probe. Insufficient lab time prevented any numerical evaluation of the diffusion constant. As previously reported,1 the lifetime for the triplet exciton, determined from the first-order components of the phosphorescence and delayed fluorescence decay curves, is 130 ± 20 msec. Impurities and exposure of the sample to the atmosphere were found to have significant effects upon the spectral characteristics of the samples.