title: Hydration of atmospherically relevant molecular clusters: computational chemistry and classical thermodynamics.
abstract: Formation of new particles through clustering of molecules from condensable vapors is a significant source for atmospheric aerosols. The smallest clusters formed in the very first steps of the condensation process are, however, not directly observable by experimental means. We present here a comprehensive series of electronic structure calculations on the hydrates of clusters formed by up to four molecules of sulfuric acid, and up to two molecules of ammonia or dimethylamine. Though clusters containing ammonia, and certainly dimethylamine, generally exhibit lower average hydration than the pure acid clusters, populations of individual hydrates vary widely. Furthermore, we explore the predictions obtained using a thermodynamic model for the description of these hydrates. The similar magnitude and trends of hydrate formation predicted by both methods illustrate the potential of combining them to obtain more comprehensive models. The stabilization of some clusters relative to others due to their hydration is highly likely to have significant effects on the overall processes that lead to formation of new particles in the atmosphere.
authors.affiliation: Division of Atmospheric Sciences, Department of Physics, University of Helsinki , P.O. Box 64, 00014 Helsinki, Finland.
authors.forename: Henning
authors.initials: H
authors.lastname: Henschel
authors.forename: Juan C Acosta
authors.initials: JC
authors.lastname: Navarro
authors.forename: Taina
authors.initials: T
authors.lastname: Yli-Juuti
authors.forename: Oona
authors.initials: O
authors.lastname: Kupiainen-Määttä
authors.forename: Tinja
authors.initials: T
authors.lastname: Olenius
authors.forename: Ismael K
authors.initials: IK
authors.lastname: Ortega
authors.forename: Simon L
authors.initials: SL
authors.lastname: Clegg
authors.forename: Theo
authors.initials: T
authors.lastname: Kurtén
authors.forename: Ilona
authors.initials: I
authors.lastname: Riipinen
authors.forename: Hanna
authors.initials: H
authors.lastname: Vehkamäki
mesh_terms: D000336:Aerosols / Q000737:chemistry; D000641:Ammonia / Q000737:chemistry; D001272:Atmosphere / Q000737:chemistry*; D004123:Dimethylamines / Q000737:chemistry; D004583:Electrons; D056004:Molecular Dynamics Simulation; D013464:Sulfuric Acids / Q000737:chemistry; D013816:Thermodynamics; D014867:Water / Q000737:chemistry
chemical_list: D000336:Aerosols; D004123:Dimethylamines; D013464:Sulfuric Acids; D014867:Water; D000641:Ammonia; C034516:dimethylamine; C033158:sulfuric acid