Reduction of the Fluorescence Transition Dipole Moment by Excitation Localization in a Vibronically Coupled Squaraine Dimer
Reduction of the Fluorescence Transition Dipole Moment by Excitation Localization in a Vibronically Coupled Squaraine Dimer
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DOI：
10.1021/acs.jpcc.8b11957
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发表时间：
2019-01
期刊：
影响因子：
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通讯作者：
H. Marciniak;Nina Auerhammer;S. Ricker;A. Schmiedel;M. Holzapfel;C. Lambert
中科院分区：
文献类型：
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作者：
H. Marciniak;Nina Auerhammer;S. Ricker;A. Schmiedel;M. Holzapfel;C. Lambert
刚性桥接方形二聚体可作为模型化合物来研究两个发色团之间的激子相互作用，而不干扰构象或其他立体化学异构体。我们描述了合成以及稳态和fs-和ps-时间分辨光谱数据。光谱解释使用一个振动耦合模型，该模型考虑一个单一的振动模式，产生一个浅激发态表面有两个最小值。这两个极小值导致激发态的对称性破缺，从而导致激发的局部定位。波函数的局域化导致荧光跃迁矩减小，尽管吸收光谱和发射光谱都显示了典型的激子耦合发色团的交换变窄。
A rigidly bridged squaraine dimer serves as a model compound to study exciton interactions between two chromophores without interfering with conformational or other stereochemical isomers. We describe the synthesis as well as steady state and fs- and ps-time-resolved optical spectroscopic data. The spectra are interpreted using a vibronic coupling model, which considers a single vibrational mode that produces a shallow excited state surface with two minima. These two minima cause symmetry breaking of the excited state, which leads to a partial localization of excitation. The localization of the wave function causes a reduced fluorescence transition moment, although both the absorption and the emission spectra display exchange narrowing typical of excitonically coupled chromophores.