Dynamics of internal rotation related to the intramolecular charge-t transfer reactions

该项目的目的是确定能够形成分子内电荷转移（CT）态的化合物的内旋转电势，然后观察扭转反应坐标上CT态形成的动力学。以下主题已得到广泛研究1。内旋转势能面的测定测定了9,9'-联二蒽(BA)-稀有气体和BA-Ar络合物的内旋转势能面。在 He 络合物中，小扰动会稍微分裂简并扭曲能级，而在 Ar 和 O 络合物中，势的形状会发生巨大变化；双井中的一井电位消失。2． BA配合物的时间分辨荧光BA-Ar配合物仅从激发的S_1态发出荧光，而BA-H_2 O配合物则从S_1和CT态发出荧光。发现 BA-Ar 荧光的时间分布与观察到的波长无关，这可能表明检测系统的时间分辨率内的快速 IVR。另一方面，BA-H_2O配合物的时间曲线显示出波长依赖性；在激发波长 375 nm 处，它在 10 ps 内衰减得非常快，而在 380 nm 处，它随着时间常数 20 ps 先增加然后减少。 CT 荧光随着 20 ps 的上升时间而增加。此行为表明中间状态的存在，该中间状态可能可分配给振动热 CT 状态3。时间分辨荧光损耗(TRFD)法观察弛豫过程用TRFD法观察到BA-Ar和BA-H_2O配合物激发态的快速失相过程。在BA-Ar配合物中，观察到的10 ps的失相时间对应于分子内振动能量的重新分布，而在BA-H_2O配合物中，观察到的6 ps的失相时间可以归因于IVR和CT状态的形成。4．动态过程的模拟 BA-H2O 复合物中同时发生的 IVR 和 CT 状态形成根据 ps 激励制备的波函数的时间演化进行了模拟。观察到的行为得到了很好的再现。较少的

The aim of this project is to determine the internal rotation potentials of the compounds capable of forming an intramolecular charge-transfer (CT) state and then to observe the dynamics of the CT state formation on the twisting reaction coordinate. The following topics have been extensively studied1. Determination of the potential energy surface of internal rotationThe potential energy surfaces for the internal rotation of 9,9'-bianthryl (BA) -rare gas and BA-Ar complexes were determined. In a He complex the small perturbation slightly splits the degenerate twisting levels whereas in Ar and O complexes the shape of the potential is drastically changed ; one well of the double well potential disappears.2. The time-resolved fluorescence of BA complexesThe BA-Ar complex only emits the fluorescence from the excited S_1 state whereas the BA-H_2 O complex gives the fluorescence from both the S_1 and the CT states. The time profile of the BA-Ar fluorescence was found to be independent of the … More wavelength observed, which probably indicated the rapid IVR within the time resolution of the detecting system. On the other hand, the time profile of the BA-H_2O complex showed the wavelength dependence ; at the excitation wavelength 375 nm), it decayd very rapidly within 10 ps whereas at 380nm it increased first and then decreased with the time constant of 20 ps. The CT fluorescence increased with 20 ps rise time. This behavior indicates the presence of the intermediate state which probably be assignable to the vibarationally hot CT state3. The observation of the relaxation processes with the time-resolved fluorescence depletion (TRFD) methodWith the TRFD method, the rapid dephasing processes of the excited state of BA-Ar and BA-H_2O complexes have been observed. In the BA-Ar complexes, the observed dephasing of 10 ps corresponded to the intramolecular vibrational energy redistribution whereas in BA-H_2O complexes the observed 6 ps dephasing time could be attributed to both the IVR and CT state formation.4. A simulation of the dynamic processesThe simultaneously occurring IVR and CT state formation in the BA-H2O complexes was simulated in terms of the time-evolution of the wavefunction prepared by the ps excitation. The observed behavior was well reproduced. Less