Redox conditions correlated with vibronic coupling modulate quantum beats in photosynthetic pigment–protein complexes
Redox conditions correlated with vibronic coupling modulate quantum beats in photosynthetic pigment–protein complexes
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与电子振动耦合相关的氧化还原条件调节光合色素-蛋白质复合物中的量子节拍
DOI：
10.1073/pnas.2112817118
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Blankenship, Robert E.
中科院分区：
文献类型：
--
作者：
Higgins, Jacob S.;Allodi, Marco A.;Lloyd, Lawson T.;Otto, John P.;Sohail, Sara H.;Saer, Rafael G.;Wood, Ryan E.;Massey, Sara C.;Ting, Po-Chieh;Blankenship, Robert E.
量子相干，在超快光谱实验中作为时间相关的拍子被观察到，当光-物质相互作用使系统处于不同能量和固定相位的叠加态时，就会出现。这种相干性已经在超快激光激发后的光合系统中被观察到，但是这些相干性意味着潜在的能量传递动力学仍然存在争议。最近的研究表明，氧化还原条件可以调节绿硫细菌中fna - matthews - olson （FMO）色素-蛋白质复合物中的振动耦合，这就提出了氧化还原条件是否也可能影响该复合物中观察到的长寿命（bbb100 fs）量子相干性的问题。在这项工作中，我们对氧化和还原条件下的FMO配合物进行了超快二维电子能谱测量。我们观察到许多激发态相干只存在于还原条件下，而在氧化条件下不存在或减弱。还原条件更接近于复合体的自然条件。此外，这些相干的存在与在还原条件下通过复合物产生更快、更有效的能量传递的振动耦合相关。在等待时间内相干的增长和功率谱中数百个波数上的跳动频率的数量表明，这些跳动是激发态相干，主要具有振动特征，其相位关系通过能量传递过程保持。我们的研究结果表明，激子的能量传递是通过一种相干机制进行的，并且这种相干可以提供一种工具，从随机环境波动驱动的能量传递中分离相干松弛。
Quantum coherences, observed as time-dependent beats in ultrafast spectroscopic experiments, arise when light–matter interactions prepare systems in superpositions of states with differing energy and fixed phase across the ensemble. Such coherences have been observed in photosynthetic systems following ultrafast laser excitation, but what these coherences imply about the underlying energy transfer dynamics remains subject to debate. Recent work showed that redox conditions tune vibronic coupling in the Fenna–Matthews–Olson (FMO) pigment–protein complex in green sulfur bacteria, raising the question of whether redox conditions may also affect the long-lived (>100 fs) quantum coherences observed in this complex. In this work, we perform ultrafast two-dimensional electronic spectroscopy measurements on the FMO complex under both oxidizing and reducing conditions. We observe that many excited-state coherences are exclusively present in reducing conditions and are absent or attenuated in oxidizing conditions. Reducing conditions mimic the natural conditions of the complex more closely. Further, the presence of these coherences correlates with the vibronic coupling that produces faster, more efficient energy transfer through the complex under reducing conditions. The growth of coherences across the waiting time and the number of beating frequencies across hundreds of wavenumbers in the power spectra suggest that the beats are excited-state coherences with a mostly vibrational character whose phase relationship is maintained through the energy transfer process. Our results suggest that excitonic energy transfer proceeds through a coherent mechanism in this complex and that the coherences may provide a tool to disentangle coherent relaxation from energy transfer driven by stochastic environmental fluctuations.
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作者：
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DOI：
--
发表时间：
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期刊：
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DOI：
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发表时间：
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影响因子：
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影响因子：
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作者：
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