Abstract: The electronic characteristics and rapid dynamics associated with bacteriochlorophyll dimers in photosynthetic systems are investigated using novel ultrafast anisotropy techniques. The excitonic structure of isolated subunits (B820) from the core (LH-1) light harvesting complex of Rs. Rubrum and the reassociated complex (B873) is revealed in coherent anisotropy responses following impulsive excitation. For B820, the oscillatory anisotropy responses indicate excitonic splitting frequencies ranging from 370 cm$+$MIN@1$/ to 490 cm$+$MIN@1$/ indicating significant inhomogeneity in the excitonic spectrum. The complete set of wavelength dependent anisotropy result is analyzed to reveal the sources of inhomogeneity for B820; correlated distributions of dimer energetic parameters are necessary to reproduce the results. The coherent response of reassociated B873 complexes exhibit multiple frequencies, revealing the extended excitonic structure of the aggregates. In other experiments, the electronic properties of the photosynthetic reaction center and the rapid electronic dynamics prior to charge separation are investigated by both 'two color' anisotropy. A variety of excitation and detection conditions provide the first room temperature characterization of the excitonic structure of the special pair, and a detailed description of rapid energy transfer to and within the special pair. The results presented here stress the importance of delocalized excitation in both the light harvesting antenna complexes and the photosynthetic reaction center. !45
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机译：摘要：利用新型超快各向异性技术研究了光合系统中细菌叶绿素二聚体的电子特性和快速动力学。 Rs的核心（LH-1）光收集复合物的分离的亚基（B820）的激子结构。在脉冲激发后，相干各向异性响应揭示了Rubrum和重新结合的复合物（B873）。对于B820，振荡各向异性响应表明激子分裂频率在370 cm $ + MIN_1 $ /至490cm + MIN + 1 $ /的范围内，表明在激子光谱中存在显着的不均匀性。分析了整套与波长相关的各向异性结果，以揭示B820不均匀的来源。二聚体能量参数的相关分布对于重现结果是必要的。重新关联的B873配合物的相干响应显示多个频率，揭示了聚集体的激子结构扩展。在其他实验中，通过“双色”各向异性研究了光合反应中心的电子性质和电荷分离之前的快速电子动力学。多种激发和检测条件提供了特殊对的激子结构的第一个室温表征，以及对特殊对和内部的快速能量传递的详细描述。这里介绍的结果强调了在光收集天线复合体和光合反应中心中离域激发的重要性。 ！45
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