Süß J, Engel V
Institut für Physikalische und Theoretische Chemie, Universität Würzburg, Emil-Fischer-Str. 42, 97074 Würzburg, Germany.
J Chem Phys. 2020 May 7;152(17):174305. doi: 10.1063/1.5134534.
The usual view of exciton-exciton annihilation (EEA) processes in molecular aggregates is based on locally excited states of the monomer units. However, the corresponding localized configurations can only be assumed if the system is in a coherent superposition of eigenstates, i.e., a wave packet. We study a molecular dimer and focus on the characterization of EEA by a wave packet motion induced in the system by ultrashort pulse excitation. Here, coherences that appear are destroyed by dissipation processes. We discuss the influence of interband and intraband relaxation on the dynamics. The states that participate in the annihilation process are directly accessible by fifth-order optical two-dimensional spectroscopy. Such spectra are calculated, and spectral features are related to the annihilation process.
分子聚集体中激子 - 激子湮灭（EEA）过程的通常观点是基于单体单元的局域激发态。然而，只有当系统处于本征态的相干叠加态，即波包时，才能假定相应的局域构型。我们研究了一个分子二聚体，并专注于通过超短脉冲激发在系统中诱导的波包运动来表征EEA。在这里，出现的相干性会被耗散过程破坏。我们讨论了带间和带内弛豫对动力学的影响。参与湮灭过程的态可通过五阶光学二维光谱直接获取。计算了此类光谱，并将光谱特征与湮灭过程相关联。
