Zakutauskaitė Kristina, Mačernis Mindaugas, Nguyen Hoang H, Ogilvie Jennifer P, Abramavičius Darius
Institute of Chemical Physics, Vilnius University, Sauletekio al. 9-III, Vilnius, Lithuania.
Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA.
J Chem Phys. 2023 Jan 7;158(1):015103. doi: 10.1063/5.0108166.
We apply Frenkel exciton theory to model the entire Q-band of a tightly bound chlorophyll dimer inspired by the photosynthetic reaction center of photosystem II. The potential of broadband two-dimensional electronic spectroscopy experiment spanning the Q and Q regions to extract the parameters of the model dimer Hamiltonian is examined through theoretical simulations of the experiment. We find that the local nature of Q excitation enables identification of molecular properties of the delocalized Q excitons. Specifically, we demonstrate that the cross-peak region, where excitation energy is resonant with Q while detection is at Q, contains specific spectral signatures that can reveal the full real-space molecular Hamiltonian, a task that is impossible by considering the Q transitions alone. System-bath coupling and site energy disorder in realistic systems may limit the resolution of these spectral signatures due to spectral congestion.
受光系统II光合反应中心的启发，我们应用弗伦克尔激子理论对紧密结合的叶绿素二聚体的整个Q带进行建模。通过对实验的理论模拟，研究了跨越Q和Q区域的宽带二维电子光谱实验提取模型二聚体哈密顿量参数的潜力。我们发现Q激发的局域性质能够识别离域Q激子的分子性质。具体而言，我们证明了交叉峰区域（其中激发能量与Q共振而检测在Q处）包含特定的光谱特征，这些特征可以揭示完整的实空间分子哈密顿量，而仅考虑Q跃迁是无法完成这项任务的。由于光谱拥挤，实际系统中的系统 - 浴耦合和位点能量无序可能会限制这些光谱特征的分辨率。
