Theoretical study of photochemical hole burning in photosynthetic bacterial reaction centers

Won, Youjip; Friesner, Richard A.

doi:10.1021/j100319a026

Cited by 48 publications

(31 citation statements)

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“…Those conclusions do not agree with those to be obtained here using the refined coordinates. The calculated S1 state, reaction fields omitted, may now be described as the lower ( P -) exciton component in which the separate Qy transition moments are added and the energy lowered, in good agreement with the results of Vermeglio and Paillotin [ 521 and others [53][54][55][56][57]. The upper component P + is closest to the S2 state, judging from Tables VI and VII.…”

Section: Spectra Of P( Bchlb) Monomerssupporting

confidence: 87%

“…The upper component P + is closest to the S2 state, judging from Tables VI and VII. The exciton couplings are calculated to be 645 cm-' which is slightly larger than assumed in parametrized models for the reaction center to obtain agreement with the spectra [55][56][57]. An exaggeration of the exciton coupling in the CNDO/S model can be expected [ …”

Section: Spectra Of P( Bchlb) Monomersmentioning

confidence: 99%

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Charge separation in 9,9?-dianthryl and a special pair treated by a semi-empirical reaction field method

Larsson

Källbring

1990

Int. J. Quantum Chem.

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Reaction fields are introduced to treat charge transfer excitations in chromophore systems. The methods are tested on the 9,9'-dianthryl dimeric molecule. The energy shift of the low energy component in dual fluorescence is a function of the polarity of the solvent and is correctly reproduced if an interpolation formula is used between the Mataga-Nishimoto and Ohno-Klopman approximations for the bi-centric y integrals. The model is then applied to the special pair of the photosynthetic reaction center of Rhodopseudomonas viridis. This special pair is found to have an s, state with dipolar character, corresponding to partial M + L charge transfer. The bias is due to the bent shape of the M chromophore.

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Section: Spectra Of P( Bchlb) Monomerssupporting

confidence: 87%

Section: Spectra Of P( Bchlb) Monomersmentioning

confidence: 99%

Charge separation in 9,9?-dianthryl and a special pair treated by a semi-empirical reaction field method

Larsson

Källbring

1990

Int. J. Quantum Chem.

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“…In our setup, we exclude the antenna and assume that the pair absorbs sunlight cooperatively via the exciton states a 1 and a 2 which are separated by the Davydov splitting (33). In bacterial systems the splitting is on the order of 450-800 wavenumbers (43), whereas in the Photosystem II reaction center, the special pair coupling is weaker (160-200 cm −1 ) (21). The remaining states are similar to those of Fig.…”

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confidence: 99%

Photosynthetic reaction center as a quantum heat engine

Dorfman

Voronine

Mukamel

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

277

339

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Two seemingly unrelated effects attributed to quantum coherence have been reported recently in natural and artificial light-harvesting systems. First, an enhanced solar cell efficiency was predicted and second, population oscillations were measured in photosynthetic antennae excited by sequences of coherent ultrashort laser pulses. Because both systems operate as quantum heat engines (QHEs) that convert the solar photon energy to useful work (electric currents or chemical energy, respectively), the question arises whether coherence could also enhance the photosynthetic yield. Here, we show that both effects arise from the same population-coherence coupling term which is induced by noise, does not require coherent light, and will therefore work for incoherent excitation under natural conditions of solar excitation. Charge separation in light-harvesting complexes occurs in a pair of tightly coupled chlorophylls (the special pair) at the heart of photosynthetic reaction centers of both plants and bacteria. We show the analogy between the energy level schemes of the special pair and of the laser/photocell QHEs, and that both population oscillations and enhanced yield have a common origin and are expected to coexist for typical parameters. We predict an enhanced yield of 27% in a QHE motivated by the reaction center. This suggests nature-mimicking architectures for artificial solar energy devices.photosynthesis | quantum biology | population oscillations | quantum coherence A ccording to the laws of quantum thermodynamics, quantum heat engines (QHEs) convert hot thermal radiation into low-entropy useful work (1, 2). The ultimate efficiency of such QHEs is usually governed by a detailed balance between absorption and emission of the hot pump radiation (3). The laser is an example of a QHE, which can use incoherent pump (heat) radiation to produce highly coherent (low-entropy) light ( Fig. 1 A and B). Moreover, it was demonstrated both theoretically and experimentally that noise-induced quantum coherence (4) can break detailed balance and yield lasers without population inversion (5) and/or with enhanced efficiency (Fig. 1C).Recently it has been shown that quantum coherence can, in principle, enhance the efficiency of a solar cell or a photodetector (6-10). This photocell QHE (Fig. 1D) can be described by the same model as the laser QHE (Fig. 1E) and obeys similar detailed balance physics. To use the broad solar spectrum and eliminate phonon loss, we separate solar flux into narrow frequency intervals and direct it onto a cell array where each of the cells has been prepared to have its band gap equal to that photon energy (7). In particular, Shockley and Queisser (11) invoked detailed balance to show that the open-circuit voltage of a photocell is related to the energy input of a "hot" monochromatic thermal light by the Carnot factor. However, just as in the case of the laser, we can, in principle, break detailed balance by inducing coherence (Fig. 1F), which can enhance the photocell efficiency (9, 10).Other recent p...

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“…Theoretical calculations based on the phenomenological exciton model (9,10) and semiempirical quantum chemical methods (1 1-1 3), in which varying degrees of parameterization are used, have demonstrated that interactions between the six chromophores (quinones can be excluded) of the RC are required for an adequate description of the Q, states. Although there is general agreement that the lowest energy excited state (P960* in Rps.…”

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confidence: 99%

A Photoinduced Persistent Structural Transformation of the Special Pair of a Bacterial Reaction Center

Reddy

Kolaczkowski

Small

1993

Science

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Structural modification of photosynthetic reaction centers is an important approach for understanding their charge-separation processes. An unprecedented persistent structural transformation of the special pair (dimer) of bacteriochlorophyll molecules can be produced by light absorption alone. The nonphotochemical hole-burned spectra for the reaction center of Rhodopseudomonas viridis show that the phototransformation leads to a red shift of 150 wave numbers for the special pair's lowest energy absorption band, P960, and a comparable blue shift for a state at 850 nanometers, which can now be definitively assigned as being most closely associated with the upper dimer component. Additional insights on excited-state electronic structure include the identification of a new state.

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Theoretical study of photochemical hole burning in photosynthetic bacterial reaction centers

Cited by 48 publications

References 0 publications

Charge separation in 9,9?-dianthryl and a special pair treated by a semi-empirical reaction field method

Charge separation in 9,9?-dianthryl and a special pair treated by a semi-empirical reaction field method

Photosynthetic reaction center as a quantum heat engine

A Photoinduced Persistent Structural Transformation of the Special Pair of a Bacterial Reaction Center

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