Long-Lived Electronic Coherence in Dissipative Exciton Dynamics of Light-Harvesting Complexes
Long-Lived Electronic Coherence in Dissipative Exciton Dynamics of Light-Harvesting Complexes
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DOI：
10.1021/jz3012029
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发表时间：
2012-10-04
影响因子：
5.7
通讯作者：
Kramer, Tobias
中科院分区：
文献类型：
--
作者：
Kreisbeck, Christoph;Kramer, Tobias
最近的实验在环境温度下的光捕获复合物显示振荡信号的二维光谱。他们提出的机制，支持相干激子运输通过分子网络在嘈杂的环境中。我们证明了一种机制，依赖于连续性质的振动谱密度。我们采用Fenna-Matthews-Olson（FMO）复合物的谱密度，并对二维谱进行非微扰计算。它们在277 K的温度下显示出持久的电子相干性高达0.3 Ps。FMO复合物中发现的光谱密度的两个重要性质出现了：（i）与高频振动的耦合很大，这是向反应中心有效传输所需的，以及（ii）零频率下光谱密度的斜率接近零。我们表明，电子相干性和快速热化敏感地依赖于光谱密度的连续部分，但可以同时实现在分子网络。
Recent experiments on light-harvesting complexes at ambient temperatures display oscillatory signals in two-dimensional spectroscopy. They suggest mechanisms supporting coherent exciton transport through molecular networks in noisy environments. We demonstrate a mechanism that relies on the continuum properties of the vibronic spectral density. We employ the spectral density of the Fenna-Matthews-Olson (FMO) complex and perform a nonperturbative calculation of two-dimensional spectra. They display long-lasting electronic coherence up to 0.3 Ps at a temperature of 277 K Two important properties of the spectral density found in the FMO complex emerge; (i) the coupling to higher-frequency vibrations is large, as required for efficient transport toward the reaction center, and (ii) the slope of the spectral density at zero frequency approaches zero. We demonstrate that electronic coherence and fast thermalization depend sensitively on the continuum part of the spectral density but can be simultaneously realized in molecular networks.