Kang Seongsoo, Kim Taeyeon, Hong Yongseok, Würthner Frank, Kim Dongho
Spectroscopy Laboratory for Functional π-Electronic Systems and Department of Chemistry, Yonsei University, Seoul 03722, South Korea.
Institut for Organische Chemie and Center for Nanosystems Chemistry, Universität Würzburg, Am Hubland, 97074 Würzburg, Germany.
J Am Chem Soc. 2021 Jul 7;143(26):9825-9833. doi: 10.1021/jacs.1c03276. Epub 2021 Jun 24.
Herein, the ultrafast photoinduced dynamics and vibrational coherences for two perylenebisimide (PBI) H-aggregates showcase the formation of the excimer state and the delocalized radical anion state in the excited state, respectively. Using femtosecond transient absorption (fs-TA) and time-resolved impulsive stimulated Raman scattering (TR-ISRS) measurements, we unveiled excited-state dynamics of PBI H-aggregates in two aspects: (1) the intermolecular interactions between PBI units in H-aggregates induce the formation of new excited states, excimer and delocalized radical anion states, and (2) the intermolecular out-of-plane along the aggregate axis and the PBI core C═C stretch Raman modes can be a crucial indicator to understand the coherent exciton dynamics in H-aggregates. Notably, those excited-state Raman modes showed stationary peak positions during the excited-state dynamics. TR-ISRS analysis provides insights into the excited-state vibrational coherences concerning the formation of the excimer and charge-delocalized state in each aggregate system.
在此，两种苝二酰亚胺（PBI）H聚集体的超快光致动力学和振动相干性分别展示了激发态下准分子态和离域自由基阴离子态的形成。通过飞秒瞬态吸收（fs-TA）和时间分辨脉冲受激拉曼散射（TR-ISRS）测量，我们从两个方面揭示了PBI H聚集体的激发态动力学：（1）H聚集体中PBI单元之间的分子间相互作用诱导形成了新的激发态，即准分子态和离域自由基阴离子态；（2）沿聚集体轴的分子间面外振动以及PBI核心C═C伸缩拉曼模式可能是理解H聚集体中相干激子动力学的关键指标。值得注意的是，那些激发态拉曼模式在激发态动力学过程中显示出固定的峰位。TR-ISRS分析为每个聚集体系统中关于准分子形成和电荷离域态的激发态振动相干性提供了见解。
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