Excitation of Biomolecules by Coherent vs. Incoherent Light: Model Rhodopsin Photoisomerization

Hoki, Kunihito; Brumer, Paul

doi:10.1016/j.proche.2011.08.019

Cited by 39 publications

(72 citation statements)

References 13 publications

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“…Further, the above approach makes clear the extent to which quantum mechanics allows a physical picture of one-photon absorption in an isolated molecule. An analogous picture arises in open systems (7,22). Any additional imposed qualitative picture may well be inconsistent with quantum mechanics.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…Short time coherent dynamics is then manifest. However, under natural circumstances (such as moonlight or sunlight) such initial time evolution (on the order of tens of femtoseconds) is totally irrelevant of the time scales associated with natural light (7). That is, after this short time, the system is in a mixture of stationary states.…”

Section: Discussion and Summarymentioning

confidence: 99%

“…elsewhere using a semiclassical approach to light-matter interactions (7,22) 29), which are distinctly different from the time-evolving coherences which are the focus of this paper. iii) Changes in the populations of energy eigenstates of the system, without the involvement of time-dependent off-diagonal ρ jk , are also mentioned below in Natural Incoherent Thermal Sources, where they are termed "incoherent dynamics.…”

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confidence: 91%

“…Is the molecular response in laboratory laser experiments that use pulsed coherent laser light (6,13,15,16) relevant when the system is irradiated with natural light, i.e., radiation arising from a thermal source that is essentially CW and highly incoherent (7,21,22)? This issue (albeit not biologically motivated) was treated some time ago using a semiclassical approach to the light-matter interaction within first-order perturbation theory (21), leading to the conclusion that the responses are very different: Isolated molecules subject to pulsed coherent laser light display subsequent coherent time evolution, whereas those subject to incoherent light from a thermal CW source do not.…”

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confidence: 99%

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Molecular response in one-photon absorption via natural thermal light vs. pulsed laser excitation

Brumer

Shapiro

2012

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

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142

163

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Photoinduced biological processes occur via one-photon absorption in natural light, which is weak, continuous wave, and incoherent, but are often studied in the laboratory using pulsed coherent light. Here, we compare the response of a molecule to these two very different sources within a quantized radiation field picture. The latter is shown to induce coherent time evolution in the molecule, whereas the former does not. As a result, the coherent time dependence observed in the laboratory experiments will not be relevant to the natural biological process. Emphasis is placed on resolving confusions regarding this issue that are shown to arise from aspects of quantum measurement and from a lack of appreciation of the proper description of the absorbed photon.T he nature of the molecular response to weak electromagnetic fields, where the probability of absorbing a photon is small, is a subject of considerable importance in light-induced biological processes. Examples include light-harvesting complexes (1-3) and vision (4-8), both of which operate in the domain of weak photon flux.Recent experimental studies have generated considerable excitement (9-11) due to the observation of long-lived coherent [electronic and vibrational (12)] quantum time evolution subsequent to pulsed laser excitation of various biomolecules (13)(14)(15)(16)(17)(18)(19). Similar enthusiasm (20) has been generated by the coherent vibrational dynamics observed in retinal isomerization induced by pulsed laser light (4, 8). These references, as well as many others, either explicitly or implicitly assume that the observed coherent time evolution is of considerable biological significance.Of particular relevance, then, is whether the observed coherent time evolution does, indeed, play a biological role. Is the molecular response in laboratory laser experiments that use pulsed coherent laser light (6,13,15,16) relevant when the system is irradiated with natural light, i.e., radiation arising from a thermal source that is essentially CW and highly incoherent (7,21,22)? This issue (albeit not biologically motivated) was treated some time ago using a semiclassical approach to the light-matter interaction within first-order perturbation theory (21), leading to the conclusion that the responses are very different: Isolated molecules subject to pulsed coherent laser light display subsequent coherent time evolution, whereas those subject to incoherent light from a thermal CW source do not. In addition, that study showed that pulsed incoherent light, which by definition is partially coherent, induces time evolution on the time scale of the pulse, i.e., the molecule responds to the time envelope of the light pulse. However, for sunlight, for example, the time scale of the envelope is hours, whereas a stationary nonevolving state is reached almost immediately.These results have profound implications for biological processes induced by weak fields (photosynthesis, vision), where the probability of single-photon absorption is small due to the low photon flux. T...

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Section: Discussion and Summarymentioning

confidence: 99%

Section: Discussion and Summarymentioning

confidence: 99%

mentioning

confidence: 91%

mentioning

confidence: 99%

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Molecular response in one-photon absorption via natural thermal light vs. pulsed laser excitation

Brumer

Shapiro

2012

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

Self Cite

142

163

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“…22 This study assumes, however, very weak system− environment coupling such that the system follows a fully Markovian dynamics. In this case, it is known that eigenstate populations and coherences are decoupled and the effect of the environment is simply to damp coherences present in the initial photoexcited state.…”

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confidence: 99%

Coherent Energy Transfer under Incoherent Light Conditions

Fassioli

Olaya-Castro

Scholes

2012

J. Phys. Chem. Lett.

102

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Recent two-dimensional electronic spectroscopy (2DES) experiments have reported evidence of coherent dynamics of electronic excitations in several light-harvesting antennae. However, 2DES uses ultrafast coherent laser pulses as an excitation source; therefore, there is a current debate on whether coherent excitation dynamics is present under natural sunlight - incoherent - illumination conditions. In this letter, we show that even if incoherent light excites an electronic state with no initial quantum superpositions among excitonic states, energy transfer can proceed quantum coherently if nonequilibrium dynamics of the phonon environment takes place. Such nonequilibrium behavior manifests itself in non-Markovian evolution of electronic excitations and is typical of many photosynthetic systems. We therefore argue that light-harvesting antennae have mechanisms that could support coherent evolution under incoherent illumination.

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Simulation of Excitation by Sunlight in Mixed Quantum-Classical Dynamics

Barbatti

2020

J. Chem. Theory Comput.

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This paper proposes a method to simulate nonadiabatic dynamics initiated by thermal light, including solar radiation, in the frame of mixed quantum-classical (MQC) methods, like surface hopping. The method is based on the Chenu–Brumer approach, which treats the thermal radiation as an ensemble of coherent pulses. It is composed of three steps: (1) sampling initial conditions from a broad blackbody spectrum, (2) dynamics propagation using conventional methods, and (3) ensemble averaging considering the field and realization time of the pulses. The application of MQC dynamics with pulse ensembles (MQC-PE) to a model system of nucleic acid photophysics showed the emergence of a steady excited-state population. In another test case, modeling retinal photophysics, MQC-PE predicted that although the photoisomerization occurs within 200 fs, it may take tens of microseconds of continuous solar irradiation to photoactivate a single retinal. Such emergent long timescales may impact our understanding of biological and technological phenomena occurring under solar radiation.

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Excitation of Biomolecules by Coherent vs. Incoherent Light: Model Rhodopsin Photoisomerization

Cited by 39 publications

References 13 publications

Molecular response in one-photon absorption via natural thermal light vs. pulsed laser excitation

Molecular response in one-photon absorption via natural thermal light vs. pulsed laser excitation

Coherent Energy Transfer under Incoherent Light Conditions

Simulation of Excitation by Sunlight in Mixed Quantum-Classical Dynamics

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