Rapid Electron Transfer in Photosynthetic Reaction Centers

Rapid Electron Transfer in Photosynthetic Reaction Centers 

Martin s group has also performed the same type of measurements to wild-type RCs of Rh. sphaeroides [77], A rapid ET takes place upon an excitation of the special pair in this system. Since the bandwidth of the pumping pulse can only cover one electronic state (special pair), quantum beats result from a generation of the vibrational coherence. However, the system also exhibits single-vibronic ET. In this case, the coupled-master equations can be written as 

Scherer s group has reported 10 fsec pump-probe measurements on mutant RCs of Rb. sphaeroides R26 [103]. In this case, at least two electronic states are involved in the pumping process so that the time development of the vibronic coherence should be considered. To perform a numerical simulation on the coupled GMEs (Eqs. (142)-(144)), one has to analyze the absorption spectra of this system first and the energies of the involved electronic states can be determined. The 77 and 298 K absorption spectra 

To construct a model for the P band, the molecular parameters are adopted from Mathies results vibrational frequencies, the coupling constants, the inhomogeneous broadening, and electronic dephasing constant, etc. A microscopic model should contain these molecular parameters. Since 

The presented theoretical approach to large molecular systems such as bacterial photosynthetic RCs can provide microscopic details of ultrafast radiationless transition taking place faster than 100 fsec. In particular, this approach establishes a standard model for treating such ultrafast processes of RCs. It is possible to analyze and provide similar details for wild-type RCs or other mutant RCs for example, for wild-type RCs of Rb. sphaeroides the electronic coupling of radiationless transition from the B band to the higher excitonic band and that from the higher excitonic band to the lower one are found to be 105.5 and 123 cm-1. For R26.Phe-a mutant RCs, the former coupling is 105 cm-1 and the latter is 123.7 cm-1. 

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