A theory of excitation transfer in photosynthetic units.

A theory of the excitation kinetics in the bacteria photosynthetic unit with regard to its globular structure is presented. It assumes that the excitation transfer between globulae is carried out by means of the mechanism of incoherent excitons, at the same time considering the finite time of the excitation fixation in the reaction center. A method of local perturbations is used with a view to finding a solution to the given problem. The expressions obtained for the fluorescence decay time and its quantum yield are discussed in connection with the multiple experiments considering the cubic as well as the hexagonal probable structure of the photosynthetic unit. The analysis given shows that the period of the excitation transfer between globulae equals 10 to 100 psec and the number of the globulae is less than 35. These conclusions fall in with the initial assumption of the energy transfer between globulae by incoherent excitons. Without considering the globularity, the consistency of the theory with experimental data becomes difficult.