Coherent motion reveals non-ergodic nature of internal conversion between excited states.
Coherent motion reveals non-ergodic nature of internal conversion between excited states.
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DOI：
10.1002/cphc.201100929
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发表时间：
2012-02
期刊：
影响因子：
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通讯作者：
T. S. Kuhlman;T. Sølling;K. B. Møller
中科院分区：
文献类型：
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作者：
T. S. Kuhlman;T. Sølling;K. B. Møller
我们发现沿低频模式的特定核运动在耦合电子态中是有效的，并且这种运动在一些小分子中普遍存在。因此，与基于标准模型的预期直接矛盾的是，对于较小的分子，内部转化过程可以进行得更快。具体来说，我们重点研究了环丁酮、环戊酮和环己酮中的S(2)→S(1)内转化。通过时间分辨质谱法和光电子能谱法，确定了这种转变的相对速率为13:2:1。值得注意的是，我们在S(2)表面上观察到环皱模式的相干核运动，并且沿着该模式的运动与对称性考虑相结合，允许对观测到的相对时间尺度进行一致的解释，而不仅仅是考虑振动态的密度或标准模型的其他方面。
We found that specific nuclear motion along low-frequency modes is effective in coupling electronic states and that this motion prevail in some small molecules. Thus, in direct contradiction to what is expected based on the standard models, the internal conversion process can proceed faster for smaller molecules. Specifically, we focus on the S(2) →S(1) internal conversion in cyclobutanone, cyclopentanone, and cyclohexanone. By means of time-resolved mass spectrometry and photoelectron spectroscopy the relative rate of this transition is determined to be 13:2:1. Remarkably, we observe coherent nuclear motion on the S(2) surface in a ring-puckering mode and motion along this mode in combination with symmetry considerations allow for a consistent explanation of the observed relative time-scales not afforded by only considering the density of vibrational states or other aspects of the standard models.