Photoinduced Charge Separation Processes in Supramolecular Triad Systems |
| The results of this paper were initially presented at The Jabłoński Centennial Conference on Luminescence and Photophysics, July 23-27, 1998, Toruń, Poland |
| K. Pirowska and J. Najbar Department of Physical Chemistry and Electrochemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland |
| Received: July 23, 1998 |
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| The nonadiabatic electron transfers in donor-acceptor-acceptor systems are investigated using three potential energy surfaces and two reaction coordinates via the stochastic Liouville equation to describe time evolution of the three excited electronic states: (1) D*-A-A, (2) D+-A--A and (3) D+-A-A-. The electronic dephasing processes are taken into account phenomenologically in terms of dephasing constants. The couplings between surfaces are effective along the intersections of pairs of surfaces in the two-dimensional coordinate space. Special situations occur in the reaction coordinate space when three surfaces are nearly degenerate. The interplay between the sequential electron transfer processes and the superexchange process is analysed for different: reorganization energies, electronic coupling, free energies for the electron transfer, dephasing rates, and temperature. The time dependent contribution of the superexchange process to the charge separation in the triad system is analysed using the time dependent rate functions. It is shown that in the nonadiabatic limit of electron transfer the influence of the electronic dephasing processes for low barrier reactions can be accounted for by appropriate changes in the reorganization energies. The present model is compared with the experimental results concerning the charge separation in the bacterial photosynthetic reaction centers. |
| DOI: 10.12693/APhysPolA.94.637 PACS numbers: 31.70.Hq, 82.30.Fi, 87.15.Rn |