Dynamics of Energy Transfer by Singlet Excitons in Naphthalene Crystals as Studied by Time-Resolved Spectroscopy

Abstract

Abstract The time-resolved sensitized fluorescence of anthracene-doped naphthalene crystals following picosecond-pulse excitation was investigated experimentally as a function of dopant concentration and temperature. The influence of the excitation intensity on the decay of pure naphthalene crystals is studied and yields an almost temperature-independent annihilation constant, yss ≈ 4 x 10-11 cm3 s-1 . The analysis of the time-resolved host and guest fluorescence shows that the energy transfer rate, kHG > changes its functional form with the guest concentration. The temperature dependence of the energy transfer rate is explained tentatively in terms of phonon relaxation and phonon promotion processes.