Pressure-Dependent Rate Constant Caused by Tunneling Effects: OH + HNO 3 as an Example
Pressure-Dependent Rate Constant Caused by Tunneling Effects: OH + HNO 3 as an Example
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隧道效应引起的压力相关速率常数：以 OH HNO 3 为例
DOI：
10.1021/acs.jpclett.0c00733
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Stanton, John F.
中科院分区：
文献类型：
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作者：
Nguyen, Thanh Lam;Stanton, John F.
对化学反应的隧道效应是众所周知的，并且已经被涉及氢原子在低温下运动的过程明确地证明了。然而，隧道效应导致衰减曲线的过程(即反应速率常数如何依赖于压力)以前显然没有文献记载。这项工作指出衰减曲线确实可以由隧道效应引起，并用简单的术语解释了这种影响。这是量子隧道的一个有趣的特征，它可以出现在低温化学中(例如在大气或星际环境中)。在这封信中，我们使用高水平耦合团簇计算结合主方程方法来研究在对流层上层和平流层下层起重要作用的OH与HNO3的反应。我们的结果结合现有的实验数据清楚地表明，隧道修正不仅取决于温度，而且还取决于压力。
Tunneling effects on chemical reactions are well-known and have been unambiguously demonstrated by processes that involve the motion of hydrogen atoms at low temperature. However, the process by which tunneling effects cause a falloff curve (i.e., how reaction rate constants depend on pressure) has apparently not been previously documented. This work points out that falloff curves can indeed be caused by tunneling and explains the effect in simple terms. This is an interesting feature of quantum tunneling, which can appear in low temperature chemistry (such as in atmospheric or interstellar environments). In this Letter, we use high-level coupled-cluster calculations in combination with master-equation methods on the well-studied reaction of OH with HNO3, which plays an important role in the upper troposphere and lower stratosphere. Our results in combination with available experimental data clearly demonstrate that the tunneling correction depends on not just temperature, but also pressure.