Photosynthetic matrix effects

The next two chapters are devoted to ultrafast radiationless transitions. In Chapter 5, the generalized linear response theory is used to treat the non-equilibrium dynamics of molecular systems. This method, based on the density matrix method, can also be used to calculate the transient spectroscopic signals that are often monitored experimentally. As an application of the method, the authors present the study of the interfadal photo-induced electron transfer in dye-sensitized solar cell as observed by transient absorption spectroscopy. Chapter 6 uses the density matrix method to discuss important processes that occur in the bacterial photosynthetic reaction center, which has congested electronic structure within 200-1500cm 1 and weak interactions between these electronic states. Therefore, this biological system is an ideal system to examine theoretical models (memory effect, coherence effect, vibrational relaxation, etc.) and techniques (generalized linear response theory, Forster-Dexter theory, Marcus theory, internal conversion theory, etc.) for treating ultrafast radiationless transition phenomena. 

There seems to be no question about the functional Importance of double bonds content of the acyl lipids. On the other hand, the contention that the fluidity per se Is a key factor governing photosynthetic capacity does not have any experimental support. The rate of the electron flow between the photosystems was Inhibited by saturation up to the level of cca. 20%, but the fluidity of the lipid matrix was even higher than at the beginning. Further Increase In lipid saturation led to an effective enhancement of mlcrovlscoslty In the deep hydrophobic core, but this has no apparent Influence on the rate of steady-state electron flow from PS II to PS I. Instead a gradual decrease observed In the rate of electron transport confined to PS II. According to our most recent studies (16), catalytic hydrogenation affects the dissociation of reduced plastoqulnone from the B protein and decreases electron transfer between the primary electron acceptor Q and the secondary acceptor, B. 

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