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Tachikawa H. Intracluster reaction dynamics of NO+(H2O)n. J Chem Phys 2024; 161:094306. [PMID: 39230376 DOI: 10.1063/5.0221836] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 08/15/2024] [Indexed: 09/05/2024] Open
Abstract
Nitric oxide (NO) and NO-water clusters play crucial roles in the D-region of the atmosphere because it is postulated that NO+ reacts with H2O to produce nitrous acid (HONO) and H3O+. HONO is the major precursor of the hydroxyl radicals leading to the formation of secondary pollutants. The sources of atmospheric HONO, however, are not fully understood. Previously, the sequential H2O addition reaction, H2O + NO+(H2O)n, and the bi-molecular collision reaction, NO+ + (H2O)n, have been investigated by both experiments and theoretical calculations to determine the formation mechanism of HONO. However, the photo-reactions from NO(H2O)n neutral clusters were not considered for the formation mechanism of HONO. In this study, the intra-cluster reactions of NO+(H2O)n clusters, following ionization of the parent neutral cluster of NO(H2O)n, were investigated using the direct ab initio molecular dynamics method. When n = 4, [NO+(H2O)4]ver [vertical ionization state of NO(H2O)n] yielded HONO and hydrated H3O+ after the intra-cluster reaction, and the reaction time was calculated to be 150 fs. The reaction is expressed as [NO+(H2O)n]ver → HONO + H3O+(H2O)n-2 (reactive) (n > 3). Larger clusters of [NO+(H2O)n]ver (n = 5-8) also yield HONO. In contrast, in smaller clusters (n = 1-3), only solvent re-orientation around NO+ occurred after the ionization: [NO+(H2O)n]ver → NO+(H2O)n (solvent re-orientation) (n = 1-3). The hydration energy of H3O+, which depends on the cluster size (n), plays an important role in promoting the formation of HONO. The reaction mechanism is discussed based on theoretical results.
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Affiliation(s)
- Hiroto Tachikawa
- Division of Applied Chemistry, Faculty of Engineering, Hokkaido University, Kita-ku, Sapporo 060-8628, Japan
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Feketeová L, Bertier P, Salbaing T, Azuma T, Calvo F, Farizon B, Farizon M, Märk TD. Impact of a hydrophobic ion on the early stage of atmospheric aerosol formation. Proc Natl Acad Sci U S A 2019; 116:22540-22544. [PMID: 31636185 PMCID: PMC6842599 DOI: 10.1073/pnas.1911136116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Atmospheric aerosols are one of the major factors affecting planetary climate, and the addition of anthropogenic molecules into the atmosphere is known to strongly affect cloud formation. The broad variety of compounds present in such dilute media and their specific underlying thermalization processes at the nanoscale make a complete quantitative description of atmospheric aerosol formation certainly challenging. In particular, it requires fundamental knowledge about the role of impurities in water cluster growth, a crucial step in the early stage of aerosol and cloud formation. Here, we show how a hydrophobic pyridinium ion within a water cluster drastically changes the thermalization properties, which will in turn change the corresponding propensity for water cluster growth. The combination of velocity map imaging with a recently developed mass spectrometry technique allows the direct measurement of the velocity distribution of the water molecules evaporated from excited clusters. In contrast to previous results on pure water clusters, the low-velocity part of the distributions for pyridinium-doped water clusters is composed of 2 distinct Maxwell-Boltzmann distributions, indicating out-of-equilibrium evaporation. More generally, the evaporation of water molecules from excited clusters is found to be much slower when the cluster is doped with a pyridinium ion. Therefore, the presence of a contaminant molecule in the nascent cluster changes the energy storage and disposal in the early stages of gas-to-particle conversion, thereby leading to an increased rate of formation of water clusters and consequently facilitating homogeneous nucleation at the early stages of atmospheric aerosol formation.
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Affiliation(s)
- Linda Feketeová
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), Institut de Physique des 2 Infinis de Lyon (IP2I) Lyon, UMR 5822, F-69622 Villeurbanne, France
| | - Paul Bertier
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), Institut de Physique des 2 Infinis de Lyon (IP2I) Lyon, UMR 5822, F-69622 Villeurbanne, France
- Atomic, Molecular & Optics (AMO) Physics Laboratory, RIKEN Cluster for Pioneering Research, 351-0198 Saitama, Japan
| | - Thibaud Salbaing
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), Institut de Physique des 2 Infinis de Lyon (IP2I) Lyon, UMR 5822, F-69622 Villeurbanne, France
| | - Toshiyuki Azuma
- Atomic, Molecular & Optics (AMO) Physics Laboratory, RIKEN Cluster for Pioneering Research, 351-0198 Saitama, Japan
| | - Florent Calvo
- Université Grenoble Alpes, CNRS, Laboratoire Interdisciplinaire de Physique (LIPhy), 38000 Grenoble, France
| | - Bernadette Farizon
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), Institut de Physique des 2 Infinis de Lyon (IP2I) Lyon, UMR 5822, F-69622 Villeurbanne, France
| | - Michel Farizon
- Université de Lyon, Université Claude Bernard Lyon 1, CNRS, Institut National de Physique Nucléaire et de Physique des Particules (IN2P3), Institut de Physique des 2 Infinis de Lyon (IP2I) Lyon, UMR 5822, F-69622 Villeurbanne, France;
| | - Tilmann D Märk
- Institut für Lonenphysik und Angewandte Physik, Leopold Franzens Universität, 6020 Innsbruck, Austria
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