Crystal–Impurity Energy Transport by Molecular Excitons in the Wave‐Like Limit: II. Diffusion in Crystals

The effect of exciton transport by diffusion on the crystal‐impurity energy transfer is investigated. It is shown that the exciton is likely to be captured by the impurity only if its distance from it is of the order of the exciton mean free path or smaller. On the basis of this argument a modified diffusion equation is developed to account for the exciton motion towards an impurity prior to capture. The equation is solved approximately in the limit of low impurity concentrations.