Die Konzentrationsabhängigkeit der Energie-Übertragung in Anthracen-Tetracen-Mischkristallen

Abstract

The relative quantum yields of the host and guest fluorescence in anthracene-tetracene mixed crystals have been measured for tetracene concentrations c T between 10 -6 and 10 -1 mol/mol and temperatures below and above the temperature region, where the energy transfer is partially quenched by shallow traps (35°K) . The concentration dependence of the quantum ratio is measured as Q T /Q A = k • cT p , where the exponent p is nearly 1 and k is measured as 6 · 10 4 and explained as the ratio τ W/ t H ( τ W is the decay time of the host fluorescence and t H the hopping time) . The fraction of transfer which is quenched at lowest temperatures is independent of the tetracene concentration. The results are compared with the exciton diffusion mechanism for energy transfer (hopping model) .