水集团离子的电子放松动态
Arthur E Bragg1, Jan R R Verlet, Aster Kammrath
1Department of Chemistry, University of California, Berkeley, California 94720, USA.
Journal of the American Chemical Society
|October 27, 2005
概括
该研究揭示了水离子中明显的电子放松通路,显示出显著的同位素效应和内部溶解和表面结合的电子同位素之间的差异. 这些发现提升了我们对水系电子动态的理解.
科学领域:
- 物理化学 物理化学
- 化学物理 化学物理
- 频谱学是一种光谱学方法.
背景情况:
- 水离子是了解水环境中的电子溶解的关键模型系统.
- 之前的研究表明,水离子中存在不同的电子结合基因,但它们的动态仍然不清楚.
研究的目的:
- 为了研究水集束离子 (H2O) 的电子放松动态, (H2O) n- .
- 要区分异构 I (内部溶解) 和异构 II (表面结合) 水离子之间的放松机制和电子结合动机.
- 探索同位素替代 (H2O与D2O) 对电子放松的影响.
主要方法:
- 时间分辨率光电子成像被用来监测p<--s激发后的超快电子演变.
- 测量了激发状态寿命和光电子角分布 (PADs).
- 对各种尺寸 (n) 的水离子进行了研究,包括同位素变体.
主要成果:
- 所有激发状态的寿命都显示出显著的同位素效应 (D2O与H2O),大约翻了一番.
- 同位体I集群 (n >= 25) 通过内部转换衰变,放松时间线性推断为50 fs,用于散水.
- 同位体II集群表现出大小独立的放松 (n=60-100),自离作为关键的衰变通道,与同位体I不同.
结论:
- 该研究证实了同位素I和同位素II水离子的独特电子放松动态和电子结合动机.
- 对于较大的同位素I集群,内部转化占主导地位,而对于同位素II,自动分离显著.
- 观察到的同位素效应为这些系统中电子放松过程的振动贡献提供了洞察力.
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