  The photoluminescence in amorphous semiconductors decays according to power
law $t^{-delta}$ at long times. The photoluminescence is controlled by
dispersive transport of electrons. The latter is usually characterized by the
power $alpha$ of the transient current observed in the time-of-flight
experiments. Geminate recombination occurs by radiative tunneling which has a
distance dependence. In this paper, we formulate ways to calculate reaction
rates and survival probabilities in the case carriers execute dispersive
diffusion with long-range reactivity. The method is applied to obtain tunneling
recombination rates under dispersive diffusion. The theoretical condition of
observing the relation $delta = alpha/2 + 1$ is obtained and theoretical
recombination rates are compared to the kinetics of observed photoluminescence
decay in the whole time range measured.
