title: Stable ammonium bisulfate clusters in the atmosphere.
abstract: Liquid drop model based equilibrium thermodynamics predicts that in the presence of even small ammonia concentrations practically all the atmospheric sulfuric acid molecules are bound to tiny, stable ammonium-bisulfate clusters. Hitherto sulfuric acid has been believed to form hydrates with water. Thermodynamic theory predicts correctly the hydrate formation observed experimentally. Results from ab initio computer simulations contradict the thermodynamic results and also the experimental findings for cluster formation in both sulfuric acid-water and ammonia-sulfuric acid-water mixtures.
authors.affiliation: Department of Physics, P.O. Box 64, 00014 University of Helsinki, Finland. hanna.vehkamaki@helsinki.fi
authors.forename: Hanna
authors.initials: H
authors.lastname: Vehkamäki
authors.forename: Ismo
authors.initials: I
authors.lastname: Napari
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala
authors.forename: Madis
authors.initials: M
authors.lastname: Noppel