通过超快电子衍射捕捉环开放在光激发的性乙乙烯中,通过键解离而引起的
Valeriu Scutelnic1, Denis S Tikhonov2, Sonia Marggi Poullain1,3
1Department of Chemistry, University of California, Berkeley, California 94720, United States.
The journal of physical chemistry letters
|May 14, 2025
概括
乙乙 (AcAc) 的光激发会在 700 fs 范围内引发快速的结构变化,如环开放和非平面化. 这些通过超快电子衍射观察到的动态发生在S1状态上,在最初的S2激发后.
科学领域:
- 物理化学 物理化学
- 化学物理 化学物理
- 分子动力学分子动力学
背景情况:
- 光诱导反应涉及跨电子状态的分子转换.
- 乙乙 (AcAc) 呈现出复杂的通路,具有形交叉点 (CI) 和系统间交叉点 (ISC).
- 气相AcAc存在于一个平面的,环状的乙醇,通过键稳定.
研究的目的:
- 在光刺激后直接探测乙乙的早期结构动力学.
- 为了阐明在刺激后的第一小秒内发生的分子转换.
- 为了将核运动与AcAc中的电子过渡相关联.
主要方法:
- 在SLAC MeV-UED设置中,超快电子衍射 (UED) 具有160 fs的时间分辨率.
- 轨迹表面跳跃模拟以建模分子行为.
- 分析UED数据以观察结构变化.
主要成果:
- 乙酸经历环开放,脱平面化和键延长在266nm光刺激后的700 fs内.
- 这些结构变化主要是由S1潜在能量表面上的核运动驱动的.
- 快速的内部转换 (<100 fs) 和随后的S2到S1转移先于观察到的动态.
结论:
- 这项研究提供了直接的结构证据,证明光激发后AcAc中的快速核动力学.
- 观察到的核运动时间尺度 (数百 fs) 与电子过渡时间尺度 (内部转换<100 fs,ISC ~1.5 ps) 不同.
- 在复杂的化学系统中,UED是研究超快速分子转换的强大工具.
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