Exciton dynamics in photosynthetic complexes: excitation by coherent and incoherent light
Exciton dynamics in photosynthetic complexes: excitation by coherent and incoherent light
复制标题
光合作用复合物中的激子动力学：相干光和非相干光的激发
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
L. Valkunas
中科院分区：
文献类型：
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作者：
T. Mančal;L. Valkunas
本文研究了一个受光源外泵浦的分子系统的动力学。在一个完全的量子力学处理，我们推导出一个通用的公式，这使我们能够评估不同的光特性的影响，在分子系统中的光诱导动力学的激发。我们表明，一旦光的属性是已知的，在一定的两点相关函数，重建系统动力学所需的唯一信息是简化的演化超算子。后一个量原则上可以通过超快非线性光谱学获得。考虑到一个小分子天线的非相干光的直接激发，我们发现，相干激发是可能的，由于与不同的激子态相关联的均匀线形的重叠。在马尔可夫近似和长期近似下，相干性的量仅在快速弛豫下是显著的，并且激子态之间的布居和相干性在长时间内都变得静态。我们还研究的情况下，当一个光合复合物的激发介导的介观系统。我们发现，这样的情况下，可以处理相同的形式主义与一个特殊的相关函数表征超快波动的介观系统。我们讨论细菌的叶绿体作为这样的介观介质的一个例子，并提出能量转移的发色团-蛋白质复合物的性质可能会特别调整到其相关的天线的波动特性。
In this paper, we consider the dynamics of a molecular system subjected to external pumping by a light source. Within a completely quantum mechanical treatment, we derive a general formula, which enables us to assess the effects of different light properties on the photo-induced dynamics of excitations in a molecular system. We show that, once the properties of light are known in terms of a certain two-point correlation function, the only information needed to reconstruct the system dynamics is the reduced evolution superoperator. The latter quantity is, in principle, accessible through ultrafast nonlinear spectroscopy. Considering a direct excitation of a small molecular antenna by incoherent light, we find that excitation of coherences is possible due to the overlap of homogeneous line shapes associated with different excitonic states. In Markov and secular approximations, the amount of coherence is significant only under fast relaxation, and both the populations and coherences between exciton states become static at long times. We also study the case when the excitation of a photosynthetic complex is mediated by a mesoscopic system. We find that such a case can be treated by the same formalism with a special correlation function characterizing ultrafast fluctuations of the mesoscopic system. We discuss bacterial chlorosome as an example of such a mesoscopic mediator and propose that the properties of energy-transferring chromophore–protein complexes might be specially tuned to the fluctuation properties of their associated antennae.