使用超快速时间分辨率红外光谱的激发状态对称性破坏的直接可视化
Bogdan Dereka1, Arnulf Rosspeintner1, Zhiquan Li2
1Department of Physical Chemistry, University of Geneva , 30 Quai Ernest-Ansermet, CH-1211 Geneva 4, Switzerland.
Journal of the American Chemical Society
|March 18, 2016
概括
在激发状态下,对称的四极分子变得双极. 这项研究揭示了溶剂极性决定了对称性破坏的动态,而溶度波动则在实时控制了转变.
科学领域:
- 摄影化学
- 分子光谱学
- 物理化学
背景情况:
- 四极分子通常在它们的电子基态中表现出对称性.
- 两光子吸收 (TPA) 研究经常显示这些分子在激发状态下表现为二极体,这种现象归因于对称性破坏.
- 这种激发状态对称性破裂的精确机制和动态仍然不完全理解.
研究的目的:
- 在D-π-A-π-D四极分子中研究激发状态对称性的实时动态.
- 阐明溶剂极性对激发状态的性质和演变的影响.
- 确定溶解动力学在规范对称性破坏过程中的作用.
主要方法:
- 使用超快速的短暂红外吸收光谱实时监测激发状态的动态.
- 合成并研究了一种具有D-π-A-π-D (捐赠者-π桥接收者-π桥捐赠者) 结构的四极分子.
- 实验涉及各种各样的溶剂极性,从非极性到极性.
主要成果:
- 在非极性溶剂中,激发状态保持对称和四极.
- 在弱极性溶剂中,最初的四极激发状态转变为不均分布的对称性破裂状态.
- 在极极性溶剂中,激发状态演变为纯二极状态,激发局限于一个分子臂.
- 观察到的过渡时间与溶剂重组动态相关.
结论:
- 在四极分子中激发状态对称性破裂是一个由溶剂极性影响的动态过程.
- 溶剂波动和溶解动力学在调节从对称到失对称和双极激发状态的过程中起着至关重要的作用.
- 观察到的行为为复杂分子系统中的激发状态进化提供了详细的,时间解决的理解.
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