Chlorosomes of green bacteria can be considered as a prototype of future artificial light-harvesting devices due to their unique property of self-assembly of a large number of bacteriochlorophyll (BChl) c/d/e molecules into compact aggregates. The presence of carotenoids (Cars) in chlorosomes is very important for photoprotection, light harvesting and structure stabilization. In this work, we studied for the first time the electrochromic band shift (Stark effect) in Cars of the phototrophic filamentous green bacterium Chloroflexus (Cfx.) aurantiacus induced by fs light excitation of the main pigment, BChl c. The high accuracy of the spectral measurements permitted us to extract a small wavy spectral feature, which, obviously, can be associated with the dynamic shift of the Car absorption band. A global analysis of spectroscopy data and theoretical modeling of absorption spectra showed that near 60% of Cars exhibited a red Stark shift of ~ 25 cm⁻¹ and the remaining 40% exhibited a blue shift. We interpreted this finding as evidence of various orientations of Car in chlorosomes. We estimated the average value of the light-induced electric field strength in the place of Car molecules as ~ 10⁶ V/cm and the average distance between Car and the neighboring BChl c as ~ 10 Å. We concluded that the dynamics of the Car electrochromic band shift mainly reflected the dynamics of exciton migration through the chlorosome toward the baseplate within ~ 1 ps. Our work has unambiguously shown that Cars are sensitive indicators of light-induced internal electric fields in chlorosomes.

绿色细菌的染色体可以被认为是未来人工光捕获装置的原型，因为它们具有将大量细菌叶绿素 (BChl) c/d/e分子自组装成致密聚集体的独特特性。染色体中类胡萝卜素 (Cars) 的存在对于光保护、光收集和结构稳定非常重要。在这项工作中，我们首次研究了由主要色素 BChl c的飞秒光激发诱导的光养丝状绿色细菌Chloroflexus ( Cfx. ) aurantiacus在汽车中的电致变色带移（斯塔克效应）. 光谱测量的高精度使我们能够提取小的波浪光谱特征，这显然与 Car 吸收带的动态偏移有关。光谱数据的全局分析和吸收光谱的理论建模表明，近 60% 的 Cars 表现出约 25 cm ^-1的红斯塔克偏移，其余 40% 表现出蓝移。我们将这一发现解释为 Car 在染色体中的各种方向的证据。我们估计 Car 分子位置的光感应电场强度的平均值为 ~ 10 ⁶  V/cm，Car 与相邻 BChl c之间的平均距离作为 ~ 10 Å。我们得出结论，Car 电致变色带位移的动力学主要反映了激子在 ~ 1 ps 内通过叶绿体向基板迁移的动力学。我们的工作明确表明，汽车是染色体中光诱导内部电场的敏感指标。