Reactivity of the O2+·(H2O)n and NO+·(H2O)n cluster ions in the D-region of the ionosphere

Sharma, Sainish; Wright, Timothy G.; Besley, Nicholas A.

Abstract

The protonated water clusters present in the D-region of the ionosphere have been postulated to be formed from cluster ions such as O2+·(H2O)n and NO+·(H2O)n, although the detailed mechanism of the underlying reactions is not understood. Second order Møller–Plesset perturbation theory based Born–Oppenheimer ab initio molecular dynamics (AIMD) simulations of the reactions of the O2+·(H2O)n and NO+·(H2O)n cluster ions to form protonated water clusters reveal different mechanisms for the O2+ and NO+ based ions. AIMD simulations of O2+·(H2O)n=2–5 with initial velocities of the atoms sampled from the Maxwell–Boltzmann distribution at 220 K show that following charge transfer, a reaction to form a protonated water cluster and OH occurs rapidly where the neutral O2 molecule is just a spectator. In contrast, the reaction of NO+·(H2O)n=4,5 has been hypothesised to involve an intracluster reaction, but no reaction is observed in AIMD simulations using thermal initial velocities. However, it is shown that reactions to form protonated water clusters do occur in simulations when a water molecule collides with a NO+·(H2O)4 cluster.

• Journal Article Type: Article
• Publication Date: Oct 2, 2018
• Journal: Physical Chemistry Chemical Physics
• Print ISSN: 1463-9076
• Electronic ISSN: 1463-9084
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 20
• Issue: 40
• Pages: 25931-25938
• APA6 Citation: Sharma, S., Wright, T. G., & Besley, N. A. (2018). Reactivity of the O2+·(H2O)n and NO+·(H2O)n cluster ions in the D-region of the ionosphere. Physical Chemistry Chemical Physics, 20(40), 25931-25938 . doi:10.1039/c8cp05681a
• DOI: https://doi.org/10.1039/c8cp05681a
• Keywords: Physical and Theoretical Chemistry; General Physics and Astronomy
• Publisher URL: https://pubs.rsc.org/en/Content/ArticleLanding/2018/CP/C8CP05681A#!divAbstract
• Additional Information: : This document is Similarity Check deposited; : Supplementary Information; : Timothy G. Wright (ORCID); : Nicholas A. Besley (ORCID); : Nicholas A. Besley (ResearcherID); : Single-blind; : Received 13 September 2018; Accepted 1 October 2018; Accepted Manuscript published 2 October 2018; Advance Article published 8 October 2018