Influence of H2O and NH3 on the reaction of HO2 with NO in troposphere: Theoretical investigation of HNO3 formation pathways

• Published in: International journal of quantum chemistry 2021-01, Vol.121 (2), p.n/a
• Main Authors: Wang, Rui, Zhang, Yongqi, Li, Aizhen, Wen, Mingjie, Geng, Zerong, Geng, Ximei, Wang, Zhuqing, Wang, Zhiyin, Lily, Makroni
• Format: Article
• Language: English
• Subjects: Ammonia; atmospheric chemistry; Chemistry; gas‐phase reaction; HO2; Nitrogen dioxide; Nitrogen tetroxide; Physical chemistry; Quantum chemistry; Quantum physics; rate constant; reaction mechanism; Troposphere
• ISSN: 0020-7608; 1097-461X
• DOI: 10.1002/qua.26432

Quantum chemical calculations at B3LYP and CCSD(T) levels have been performed to investigate the effects of X (X = H2O, (H2O)2, NH3, and H3N···H2O) on HNO3 formation by the direct (HO2 + NO → HNO3) and indirect (N2O4 + H2O → HONO + HNO3) reaction of HO2 + NO. The results show that, for the direct H2O‐assisted reaction, the entrance of H2O···HO2 and NO is more important than the three other channels of HO2···H2O + NO, H2O···NO + HO2, and NO···H2O + HO2. In the H2O···HO2 + NO reactions, (H2O)2, NH3, and H3N···H2O have also been taken into account and substituted in place of H2O; however, their contributions are negligible compared with the H2O···HO2 + NO reaction. It is noted that the atmospheric gas‐phase reaction of H2O···HO2 + NO is not only competitive with the HO2 + NO2 → HNO3 reaction but can also compete well with the NO2 + HO reaction during the day and night at 298 K. Unlike the direct reaction assisted by X, the catalytic effect taken from X can be neglected in the indirect reaction of N2O4 + H2O → HONO + HNO3. However, theoretical results of the direct and indirect reaction of HO2 + NO above may be the main reason why the yield of HNO3 formation in HO2 + NO reaction increases experimentally in the presence of water. Graphic The effect of H2O, (H2O)2, NH3, and H3N···H2O on the HO2 + NO → HNO3 reaction was explored. The effect of H2O is more obvious than the three other molecules of (H2O)2, NH3, and H3N···H2O. At 298 K, the H2O···HO2 + NO reaction can not only compete with the naked HO + NO2 reaction but can also compete well with the NO2 + HO reaction during both the day and the night.