Temperature and wavelength dependence of the fluorescence lifetime of anthracene crystals

The effect of temperature (from 10 K to 300 K), crystal thickness, and fluorescence wavelength (at 10 and 300 K), on fluoresence lifetime for anthracene single crystal is studied. The effect was attributed to 1) reabsorption due to change of lifetime with thickness and 2) two guest fluorescing levels in thermal equilibriumn with the singlet exciton. This is in agreement with some of the reported results. The effect of fluorescence wavelength was interpreted in terms of the suggested time dependent reabsorption model. This model has been confirmed with the results obtained at two different temperatures.