Simulation Verification of Barrierless HONO Formation from the Oxidation Reaction System of NO, Cl, and Water in the Atmosphere
Simulation Verification of Barrierless HONO Formation from the Oxidation Reaction System of NO, Cl, and Water in the Atmosphere
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大气中NO、Cl、水氧化反应体系无障碍生成HONO的模拟验证
DOI：
10.1021/acs.est.1c01773
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发表时间：
2021
影响因子：
11.4
通讯作者：
Wenxing Wang
中科院分区：
文献类型：
--
作者：
Xianwei Zhao;Xiangli Shi;Xiaohui Ma;Junjie Wang;Fei Xu;Qingzhu Zhang;Ying Li;Zhuochao Teng;Yanan Han;Qiao Wang;Wenxing Wang
亚硝酸（HONO）是羟基（OH）自由基的主要来源，确定其来源对大气化学至关重要。本文通过Born-Oppenheimer分子动力学模拟和亚稳态模拟，发现了NO与Cl自由基在一个或两个水分子[（Cl）（NO）（H2O）n（n= 1-2）]的辅助下以及在液滴表面反应生成HONO的新途径。（Cl）（NO）（H2O）1（一水合物）体系表现出约0.95 kcal mol-1的自由能垒，而（Cl）（NO）（H2O）2（二水合物）体系是无垒的。对于二水合物体系和NO与液滴表面Cl自由基的反应，只有一个水分子参与反应，另一个水分子充当“溶剂”分子。结果表明，在东海，一水体系（[NO] = 8.56 × 1012 molecular cm-3，[Cl] = 8.00 × 106 molecular cm-3，[H2O] = 5.18 × 1017 molecular cm-3）的HONO生成速率分别占1号站位未知值的40.3%和2号站位未知值的53.8%。本研究确定了NO，Cl和水分子的反应体系在海洋边界层区域HONO形成中的重要性。
Nitrous acid (HONO) is a major source of hydroxyl (OH) radicals, and identifying its source is crucial to atmospheric chemistry. Here, a new formation route of HONO from the reaction of NO with Cl radicals with the aid of one or two water molecules [(Cl) (NO) (H2O)n(n= 1–2)] as well as on the droplet surface was found by Born–Oppenheimer molecular dynamic simulation and metadynamic simulation. The (Cl) (NO) (H2O)1(monohydrate) system exhibited a free-energy barrier of approximately 0.95 kcal mol–1, whereas the (Cl) (NO) (H2O)2(dihydrate) system was barrierless. For the dihydrate system and the reaction of NO with Cl radicals on the droplet surface, only one water molecule participated in the reaction and the other acted as the “solvent” molecule. The production rates of HONO suggested that the monohydrate system ([NO] = 8.56 × 1012molecule cm–3, [Cl] = 8.00 × 106molecule cm–3, [H2O] = 5.18 × 1017molecule cm–3) could account for 40.3% of the unknown HONO production rate (Punknown) at site 1 and 53.8% ofPunknownat site 2 in the East China Sea. This study identified the importance of the reaction system of NO, Cl, and water molecules in the formation of HONO in the marine boundary layer region.