Insights into the formation of hydroxyl radicals with nonthermal vibrational excitation in the meinel airglow
Insights into the formation of hydroxyl radicals with nonthermal vibrational excitation in the meinel airglow
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深入了解梅内尔气辉中非热振动激发羟基自由基的形成
DOI：
10.1021/acs.jpclett.1c00159
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发表时间：
2021
影响因子：
5.7
通讯作者：
Daiqian Xie
中科院分区：
文献类型：
--
作者：
Qixin Chen;Xixi Hu;Hua Guo;Daiqian Xie
为了理解Meinel带的夜间气辉和高层大气中高激发OH自由基通过重要的大气反应H + O3→ OH + O2的热转换，本文报道了在最近发展的全维势能面（PES）上对反应动力学的准经典轨线研究.我们的研究结果表明，这种高度放能反应的反应能量几乎完全被引导到OH产物的振动中，强调了从统计极限的极端偏离。计算出的OH振动分布是高度倒置的，峰值附近的最高可访问的振动状态，与实验观察非常一致，验证PES的准确性。更重要的是，OH振动模式的非热激发的动力学起源是由其在入口通道中的一个小势垒处的反应坐标上的大投影确定的，该势垒控制着产品中各种自由度的能量流。
To understand night time airglow in the Meinel bands and heat conversion from the highly excited OH radicals in the upper atmosphere via the important atmospheric reaction H + O3→ OH + O2, we report here a quasi-classical trajectory study of the reaction dynamics on a recently developed full-dimensional potential energy surface (PES). Our results indicate that the reaction energy of this highly exoergic reaction is almost exclusively channeled into the vibration of the OH product, underscoring an extreme departure from the statistical limit. The calculated OH vibrational distribution is highly inverted and peaks near the highest accessible vibrational state, in excellent agreement with experimental observations, validating the accuracy of the PES. More importantly, the dynamical origin of the nonthermal excitation of the OH vibrational mode is identified by its large projection onto the reaction coordinate at a small potential barrier in the entrance channel, which controls the energy flow into various degrees of freedom in the products.