Dynamics of excitation in systems with a randomly modulated decay channel

We have investigated the kinetics of excitation in the frame of the conventional Pauli master equation for a molecular aggregate with a decay channel attached to one distinguished molecule (or site). As a principally new feature we assume the rate of probability flow through the decay channel to be a randomly modulated function of time. The modulation is described by a Markoff stochastic process and we do not invoke the white-noise assumption. An exact calculation is given for a broad family of stochastic processes which bridges (and includes) the asymmetric random telegraph signal and the Gaussian process. The general method is then applied in three physically relevant situations: one-molecule aggregate, cyclic-antenna system and infinite linear chain. In these models, we discuss the site-occupation probabilities, the aggregate-excitation function and the mean de-excitation time.