Lambert Christoph, Hoche Joscha, Schreck Maximilian H, Holzapfel Marco, Schmiedel Alexander, Selby Joshua, Turkin Arthur, Mitric Roland
Institut für Organische Chemie, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
J Phys Chem A. 2021 Apr 1;125(12):2504-2511. doi: 10.1021/acs.jpca.1c00349. Epub 2021 Mar 19.
A squaraine heterotriad consisting of three different covalently linked squaraine chromophores was synthesized, and its absorption spectra were interpreted in terms of Kasha's exciton coupling theory. Using the exciton couplings derived from model dyads (ca. 700 cm) as the input, we were able to predict the exciton state energies of the heterotriad. Transient absorption spectroscopy with femtosecond time resolution showed that excitation of the highest exciton state populates a state mainly localized at one terminal squaraine chromophore, and energy transfer to the lowest exciton state localized at the other terminal squaraine occurs within 30 fs. Field-induced surface hopping dynamics simulations support the assumption of ultrafast energy transfer. Moreover, they show the close relationship between internal conversion and energy transfer in the intermediate to weak coupling regime. The latter is a consequence of excitation localization caused by molecular vibrations.
合成了一种由三个不同的共价连接的方酸发色团组成的方酸异三聚物，并根据卡沙激子耦合理论对方酸异三聚物的吸收光谱进行了解释。利用从模型二元化合物（约700 cm）导出的激子耦合作为输入，我们能够预测异三聚物的激子态能量。具有飞秒时间分辨率的瞬态吸收光谱表明，最高激子态的激发使主要定域在一个末端方酸发色团上的态布居，并且在30 fs内发生向定域在另一个末端方酸上的最低激子态的能量转移。场诱导表面跳跃动力学模拟支持超快能量转移的假设。此外，它们显示了中间到弱耦合区域内的内转换与能量转移之间的密切关系。后者是由分子振动引起的激发定域的结果。
