The effect of memory in the stochastic master equation analyzed using the stochastic Liouville equation of motion - Electronic energy migration transfer between reorienting donor-donor, donor-acceptor chromophores

This paper discusses the process of energy migration transfer within reorientating chromophores using the stochastic master equation (SME) and the stochastic Liouville equation (SLE) of motion. We have found that the SME over-estimates the rate of the energy migration compared to the SLE solution for a case of weakly interacting chromophores. This discrepancy between SME and SLE is caused by a memory effect occurring when fluctuations in the dipole-dipole Hamiltonian (H(t)) are on the same timescale as the intrinsic fast transverse relaxation rate characterized by (1/T-2). Thus the timescale critical for energy-transfer experiments is T-2 approximate to 10(-13) s. An extended SME is constructed, accounting for the memory effect of the dipole-dipole Hamiltonian dynamics. The influence of memory on the interpretation of experiments is discussed. (C) 2004 Elsevier B.V. All rights reserved.