University of Groningen, Zernike Institute for Advanced Materials, 9747 AG Groningen, The Netherlands.
Department of Chemistry and Hylleraas Centre for Quantum Molecular Sciences, University of Oslo, Sem Sælands vei 26, 0315 Oslo, Norway.
J Phys Chem B. 2023 Feb 9;127(5):1097-1109. doi: 10.1021/acs.jpcb.2c07143. Epub 2023 Jan 25.
Chlorosomes are supramolecular aggregates that contain thousands of bacteriochlorophyll molecules. They perform the most efficient ultrafast excitation energy transfer of all natural light-harvesting complexes. Their broad absorption band optimizes light capture. In this study, we identify the microscopic sources of the disorder causing the spectral width and reveal how it affects the excited state properties and the optical response of the system. We combine molecular dynamics, quantum chemical calculations, and response function calculations to achieve this goal. The predicted linear and two-dimensional electronic spectra are found to compare well with experimental data reproducing all key spectral features. Our analysis of the microscopic model reveals the interplay of static and dynamic disorder from the molecular perspective. We find that hydrogen bonding motifs are essential for a correct description of the spectral line shape. Furthermore, we find that exciton delocalization over tens to hundreds of molecules is consistent with the two-dimensional electronic spectra.
类囊体是包含数千个细菌叶绿素分子的超分子聚集体。它们执行所有天然光捕获复合物中最有效的超快激发能量转移。它们的宽吸收带优化了光捕获。在这项研究中，我们确定了导致光谱宽度的无序的微观来源，并揭示了它如何影响激发态性质和系统的光学响应。我们结合分子动力学、量子化学计算和响应函数计算来实现这一目标。预测的线性和二维电子光谱与实验数据吻合较好，重现了所有关键的光谱特征。我们对微观模型的分析从分子角度揭示了静态和动态无序的相互作用。我们发现氢键模式对于正确描述光谱线形状至关重要。此外，我们发现激子在数十到数百个分子上的离域与二维电子光谱一致。
