Time-dependent non-equilibrium exciton diffusion in an organic glass

Decay of donor phosphorescence is used as a sensor for time-dependent diffusion of triplet excitons in an amorphous organic solid (benzophenone) where diagonal disorder of the hopping sites prevails. The exciton jump rate is found to follow a tα-1 law. Between 4·2 K and 100 K the dispersion parameter α increases from 0·25 to 0·55. The results are compared with computer simulations based on experimental data for the density-of-states distribution.