Reddy S Rajagopala, Coto Pedro B, Thoss Michael
Institute of Physics, Albert-Ludwigs University Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany.
Department of Physical and Analytical Chemistry, University of Oviedo, Avda. Julián Clavería 8, 33006, Oviedo, Spain.
J Chem Phys. 2019 Jul 28;151(4):044307. doi: 10.1063/1.5109897.
We analyze the dynamics of intramolecular singlet fission in a series of pentacene-based dimers consisting of two pentacene-like chromophores covalently bonded to a phenylene linker in ortho, meta, and para positions. The study uses a quantum dynamical approach that employs a model vibronic Hamiltonian whose parameters are obtained using multireference perturbation theory methods. The results highlight the different role of the direct and mediated mechanism in these systems, showing that the population of the multiexcitonic state, corresponding to the first step of the intramolecular singlet fission process, occurs mainly through a superexchange-like mechanism involving doubly excited or charge transfer states that participate in the process in a virtual way. In addition, the systems investigated provide insight into the roles that built-in geometrical constraints and the electronic structure of the spacer play in the intramolecular singlet fission process.
我们分析了一系列并五苯类二聚体中分子内单重态裂变的动力学，这些二聚体由两个类似并五苯的发色团通过亚苯基连接基共价连接在邻位、间位和对位组成。该研究采用了一种量子动力学方法，该方法使用了一个模型振动哈密顿量，其参数通过多参考微扰理论方法获得。结果突出了直接机制和介导机制在这些系统中的不同作用，表明对应于分子内单重态裂变过程第一步的多激子态的布居主要通过一种类似超交换的机制发生，该机制涉及以虚拟方式参与该过程的双激发态或电荷转移态。此外，所研究的系统还深入了解了内置几何约束和间隔基的电子结构在分子内单重态裂变过程中所起的作用。
