Ab initio studies of O2−(H2O)n and O3−(H2O)n anionic molecular clusters, n≤12 1National Space Institute, Technical University of Denmark, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
21 Jul 2011
2Department of Chemistry, H.C. Ørsted Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
3Division of Atmospheric Sciences and Geophysics, Dept. of Physics, P.O. Box 64, 00014 University of Helsinki, Finland
Received: 17 Mar 2011 – Published in Atmos. Chem. Phys. Discuss.: 06 May 2011 Abstract. An ab initio study of gaseous clusters of O2− and O3− with
water is presented. Based on thorough scans of configurational space, we
determine the thermodynamics of cluster growth. The results are in good
agreement with benchmark computational methods and existing experimental
data. We find that anionic O2−(H2O)n
clusters are thermally stabilized at typical atmospheric conditions for at
least n = 5. The first 4 water molecules are strongly bound to the anion
due to delocalization of the excess charge while stabilization of more than 4
H2O is due to normal hydrogen bonding. Although clustering up to 12
H2O, we find that the O2 and O3 anions retain at least ca. 80 %
of the charge and are located at the surface of the cluster. The O2−
and O3− speicies are thus accessible for further reactions.
We consider the distributions of cluster sizes as function of altitude before
finally, the thermodynamics of a few relevant cluster reactions are considered.
Revised: 12 Jul 2011 – Accepted: 13 Jul 2011 – Published: 21 Jul 2011
Citation: Bork, N., Kurtén, T., Enghoff, M. B., Pedersen, J. O. P., Mikkelsen, K. V., and Svensmark, H.: Ab initio studies of O2−(H2O)n and O3−(H2O)n anionic molecular clusters, n≤12, Atmos. Chem. Phys., 11, 7133-7142, doi:10.5194/acp-11-7133-2011, 2011.