Abstract :
Analytical expressions for the eigenvalues and eigenvectors of the rate constants matrix describing the excitation energy transfer for a cyclic geometry of the photosynthetic unit are obtained. For a general geometry of the photosynthetic unit, the perturbation theory is used. Solutions of the Pauli Master Equation for both cases are found and discussed in detail. It is shown that for sufficiently long times these solutions as well as corresponding fluorescence intensity and other related experimental quantities behave mono-exponentially.