Exciton Localization in Extended π-Electron Systems: Comparison of Linear and Cyclic Structures.
Exciton Localization in Extended π-Electron Systems: Comparison of Linear and Cyclic Structures.
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扩展 π 电子系统中的激子局域化：线性结构和环状结构的比较。
DOI：
10.1021/acs.jpcb.5b02091
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
J. Lupton
中科院分区：
文献类型：
--
作者：
A. Thiessen;D. Würsch;S. Jester;A. V. Aggarwal;Alissa Idelson;S. Bange;J. Vogelsang;S. Höger;J. Lupton
我们采用五种不同分子形状的π共轭模型材料-低聚体和环状结构-研究了光激发后分子框架的激子自捕获和扭转运动的程度。我们的研究将系综中的稳态和瞬态荧光光谱与单分子的极化各向异性测量相结合，并由蒙特卡罗模拟支持。二聚体在光激发后表现出明显的光谱红移，这是由于扭转弛豫。这种松弛机制在结构刚性大环类似物中被抑制。然而，这两种体系都表现出高度的激子局域化，但结果却截然不同：在大周期中，激子随机定位在环的不同部分，导致极化记忆混乱；在二聚体中，局域化导致激子位置具有偶极子发光特征的确定性。蒙特卡罗模拟允许我们用无序参数量化π共轭体系的发射单元和吸收单元之间的结构差异。
We employ five π-conjugated model materials of different molecular shape-oligomers and cyclic structures-to investigate the extent of exciton self-trapping and torsional motion of the molecular framework following optical excitation. Our studies combine steady state and transient fluorescence spectroscopy in the ensemble with measurements of polarization anisotropy on single molecules, supported by Monte Carlo simulations. The dimer exhibits a significant spectral red shift within ∼100 ps after photoexcitation which is attributed to torsional relaxation. This relaxation mechanism is inhibited in the structurally rigid macrocyclic analogue. However, both systems show a high degree of exciton localization but with very different consequences: while, in the macrocycle, the exciton localizes randomly on different parts of the ring, scrambling polarization memory, in the dimer, localization leads to a deterministic exciton position with luminescence characteristics of a dipole. Monte Carlo simulations allow us to quantify the structural difference between the emitting and absorbing units of the π-conjugated system in terms of disorder parameters.
影响因子：
21.8
作者：
Aggarwal, A. Vikas;Thiessen, Alexander;Lupton, John M.
通讯作者：
Lupton, John M.
影响因子：
16.6
作者：
Chaudhuri, Debangshu;Sigmund, Eva;Lupton, John M.
通讯作者：
Lupton, John M.