Electronic coherence transfer in photosynthetic complexes and its signatures in optical spectroscopy
Abstract
Effects of electronic coherence transfer after photoexcitation of excitonic complexes and their manifestation in optical spectroscopy are discussed. Temperature dependence of the absorption band maximum of a simple excitonic dimer is interpreted in terms of coherence transfer between two excited states. The role of reorganization energy of the transitions in the magnitude of the effect is discussed.
A large reorganization energy difference between the two states is found to induce significant band shift. As an example of a time-dependent spectroscopic method sensitive to coherences and possibly to their transfer, we present recent two-dimensional photon echo measurements of energy relaxation in the so-called Fenna-Matthews-Olson complex of Chlorobium tepidum, where distinct oscillatory patters predicted to be signatures of electronic coherence have been observed.