Theoretical study on nonlinear and quantum optical phenomena of dendritic systems interacting with quantum laser field

人们从理论和计算上研究了包括树枝状结构在内的超分子体系与激光场相互作用的各种物理和化学现象。主要研究成果如下：1.发展了一种处理多态模型与各种量子场相互作用的通用计算方法，并研究了多光子过程这一非线性光学效应对动力学的影响。特别是，我们发展了一种新的方法，利用量子主方程方法来处理分子振动和碰撞对动力学的驰豫效应。对于与双模量子场相互作用的二聚体模型系统，发现分子间偶极-偶极相互作用对二聚体系统激发态布居的崩塌-复苏现象的振荡幅度和复苏时间有显著的影响。二聚体体系的纯相态和布居弛豫对…有破坏作用更重要的是二聚体电子态之间的相干，导致分子的非线性光学效应显著减弱。激子弛豫速率和外量子场的量子统计对树枝状体系的动力学和非线性光学现象的影响正在被研究。2.为了阐明结构-性质关系，我们研究了包括树枝状体系在内的超分子体系的光捕获和动态非线性光学现象。发展了一种新的单激子分子聚集体模型体系动态非线性光学性质的计算方法，并将其应用于不同激子迁移率的纳米STAR树枝状聚集体体系的非线性光谱计算。激子-声子耦合引起的激子迁移引起的纯退相现象，使光谱宽度显著增加，峰值显著降低。为了处理实际的超分子体系，如树枝状大分子，我们发展了基于从头算分子轨道组态相互作用(CI)的量子主方程方法，并阐明了有效的定向能量迁移源于π共轭通过间位取代苯环的部分穿透。我们还开始把开壳分子作为超分子体系的一个单元(积木)来考察，并从理论上发现，非线性光学效应显著地依赖于自旋态和双自由基性质。这一吸引人的结果有望成为非线性光学材料领域中一类新的体系。较少

Various physical and chemical phenomena for the interaction between supramolecular systems including dendritic systems and laser fields have been investigated theoretically and computationaly. The achievements are described as follows.1.We have developed a general calculation method treating multi-state model interacting with various quantum fields and investigated the effects of multi-photon process, which is one of nonlinear optical effects, on such dynamics. In particular, we have developed a novel method treating relaxation effects caused by molecular vibration and collision on the dynamics using a quantum master equation approach. For a dimer model system interacting with a two-mode quantum field, the collapse-revival phenomena of excited state population for dimer systems are found to be remarkably affected in oscillation amplitude and revival time by the intermolecular dipole-dipole interaction. The pure-phase and population relaxations of dimer systems are turned out to destroy … More the coherency between dimer electronic states, leading to the significant attenuation of molecular nonlinear optical effects. Several additional effects, i.e., exciton relaxation rates and quantum statistics of external quantum fields, on the dynamics and nonlinear optical phenomena of dendritic systems are now being investigated.2.We have studied light harvesting and dynamic nonlinear optical phenomena of supramolecular systems including dendritic systems in order to elucidate the structure-property relationship. A novel calculation method of dynamic nonlinear optical properties of one-exciton molecular aggregate model systems have been developed and applied to the calculation of nonlinear optical spectra of nanostar dendritic aggregate systems with various exciton migration rates. The pure-dephasing caused by the exciton migration originating in the exciton-phonon coupling has been turned out to significantly increase the spectrum width and decrease the peak. In order to treat real supermolecular systems, e.g., dendrimers, we have developed a quantum master equation method based on the ab initio molecular orbital configuration interaction (CI) and have clarified that the efficient directed energy migration originates in the partial penetration of πconjugation through meta-substituted benzene ring. We have also started to examine the open-shell molecules as a unit (building block) of supramolecular systems, and have theoretically found that the nonlinear optical effects significantly depend on the spin state and diradical character. This attractive result is expected to be a novel class of systems in the field of nonlinear optical materials. Less