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Study on the Electronic Structure of the Excited States and its Reaction of Triple Bond Conjugated Molecules

三键共轭分子激发态电子结构及其反应的研究

基本信息

批准号：
11440210
负责人：
TERO Shozo
金额：
$ 5.7万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

The following are the main results obtained in the present study.(1) Diphenylpolyynes (DPY) have a linear planar structure belonging to the D_<2h> point group in the T_1 states, which were assigned to ^3B_<1u> (π_xπ_x^*) in character.(2) The T_1 (π_xπ_x^*) states of DPY have unusually large negative D values for the ZFS parameters that increase with increasing the molecular size.(3) The large negative D value was interpreted in terms of the spin-orbit interaction between the T_1(^3π_xπ_x^*) state and the upper-lying ^3Au (π_xπ_y^*) state.(4) The energy gap between these two states was determined from the observed D values and the calculation of the spin-orbit matrix, indicating that the value decreases with increasing the number of triple bonds.(5) The rapid radiationless transition was also found in the decay from the T_1 state to the S_0 state. The k_<nr> value increases with the decrease in the energy separation between the T_1 and S_0 states, indicating the importance of the Franck-Condon factor between them for the nonradiative deactivation.(6) The appearance of the satellites due to the b_<1g> vibronic bands in the phosphorescence spectra of DPY suggests that the potential surface in the T_1 states would be shallow along the b_<1g> coordinate by the vibronic coupling between the T_1 (π_xπ_x^*) and the ^3π_xπ_y states promoted by the ring twisting motion.(7) Therefore, it is concluded that the energy proximity between the T_1 (^3B_<1u>:π_xπ_y^*) and Tu(^3Au:π_xπ_y^*) states in DPY not only increases the negative D values of the ZFS parameters by the spin-orbit interaction but also accelerates the nonradiative decay from the T_1 state by the vibronic interaction.

主要研究结果如下：(1)二苯基多炔(DPY)在T_1态具有线形平面结构，属于D_1h&gt；点群，归属为^3B_；1u&gt；(2)DPY的T_1(π_xπ_x^*)态具有异常大的负D值，其ZFS参数随分子尺寸的增大而增大。(3)大的负D值由T_1(^3π_xπ_x^*)态与上层^3AU(π_xπ_y^*)态之间的自旋-轨道相互作用来解释。(4)这两种态之间的能隙是由观测的D值和自旋轨道矩阵的计算确定的。(5)从T_1态到S_0态的衰变过程中也出现了快速的无辐射跃迁。K&lt；nr&gt；值随着T_1态与S_0态之间能量间隔的减小而增大，表明它们之间的Franck-Condon因子对于非辐射失活的重要性。(6)DPY磷光光谱中b&lt；1g&gt；振动带卫星的出现表明，T_1态的势面沿b&lt；1g&gt；通过T_1(π_xπ_x^*)态与环扭转运动促进的^3个π_xπ_y态之间的振动耦合而得到的坐标。(7)由此得出结论：DPY中T_1(^3B_&lt；1u&gt；：π_xπ_y^*)态与Tu(^3AU：π_xπ_y^*)态之间的能量接近不仅增加了自旋-轨道相互作用导致的ZFS参数的负D值，而且还加速了振动相互作用从T_1态开始的非辐射衰变。