Spectral exhibition of electron-vibrational relaxation in P* state of Rhodobacter sphaeroides reaction centersстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 11 августа 2015 г.
Аннотация:Electron-vibrational relaxation in the excited state of the primary electron donor, bacteriochlorophyll dimer P, in the reaction centers (RCs) of purple photosynthetic bacteria Rhodobacter sphaeroides is modeled. A multimode model of three states (i.e. the ground state Рg, initially excited Р1*, and relaxed excited Р2*) is used to calculate the incoherent dynamics of the difference (ΔА) spectra on a femtosecond timescale for the YM210W mutant RCs. The relaxation processes is described by the step-ladder model. The model shows that the electron-vibrational relaxation in the excited state of P is visualized by the transient red shift of the stimulated emission from P*. The dynamics of this shift is observed as a change in the ΔА spectrum shape in its red-most part, within a few hundreds of femtoseconds after excitation. As a result, an initial rise in the red-side ΔА kinetics is delayed with respect to the blue-side kinetics. The time constant of the Р1*→Р2* electronic relaxation (54 fs) and the Рg, Р1*, and Р2* vibrational relaxations (120 fs), used in the model, provided the best fit of the experimental time-resolved ΔА spectra and kinetics at 90 and 293 K. The possible nature of the Р1*→Р2* electronic relaxation is discussed.