替代模式对 thiopyridone异构体内部转换和系统间交叉的动态的影响
Douglas Garratt1, Sambit K Das2, Kacie J Nelson3
1Linac Coherent Light Source (LCLS), SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, CA 94025, USA.
Physical chemistry chemical physics : PCCP
|July 11, 2025
概括
调查皮里 (TP) 异构体发现,替代模式显著影响超快的内部转换和系统间交叉动态. 由于中间稳定,正位异构体表现出比帕异构体更快的系统间交叉.
科学领域:
- 光化学和光物理学
- 超快速光谱法 超快速光谱法
- 理论化学 理论化学
背景情况:
- 提奥皮里 (TP) 异构体对于理解分子动力学至关重要.
- 内部转换 (IC) 和系统间交叉 (ISC) 是激发状态放松的关键过程.
- 区分不同的兴奋状态 (ππ*,nπ*,单元,三元) 是至关重要的,但具有挑战性.
研究的目的:
- 为了研究溶液中的2-TP和4-TP异构体的超快IC和ISC动态.
- 确定功能组替代和溶剂对这些动态的影响.
- 使用先进的光谱学方法,区分 ππ* 和 nπ* 兴奋状态和单元/三元状态.
主要方法:
- 结合实验和理论方法.
- 超快速的短暂X射线吸收光谱 (XAS) 在硫K边缘.
- 电子激发状态的表面跳跃分子动力学模拟.
- 激发状态XAS的模拟.
主要成果:
- 在乙尼中的2-TP中,S2 (ππ*) 快速经历IC到S1 (nπ*),其次是ISC到T1 (ππ*) 在600 fs.
- 对于4-TP,S2到S1 IC需要330 fs,ISC到T1需要10 ps.
- 在介导ISC时,nπ*中间体起着至关重要的作用,其稳定/不稳定影响ISC率.
- 溶剂从酸转换为水对放松机制的影响很小.
结论:
- TP异构体的替代模式显著改变了IC和ISC时间表.
- 由于nπ*中间体的作用,正态异构体 (2-TP) 的ISC比偏态异构体 (4-TP) 快.
- 超快速XAS与理论模拟相结合,为研究激发状态动态提供了强大的工具,特别是对于nπ*状态.
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