title: Two-component heterogeneous nucleation kinetics and an application to Mars.
abstract: We develop a two-component heterogeneous nucleation model that includes exact calculation of the Stauffer-type [D. Stauffer, J. Aerosol Sci. 7, 319 (1976)] steady-state kinetic prefactor using the correct heterogeneous Zeldovich factor for a heterogeneous two-component system. The model, and a simplified version of it, is tested by comparing its predictions to experimental data for water-n-propanol nucleating on silver particles. The model is then applied to water-carbon dioxide system in Martian conditions, which has not been modeled before. Using the ideal mixture assumption, the model shows theoretical possibilities for two-component nucleation adjacent to the initial stages of one-component water nucleation, especially with small water vapor amounts. The numbers of carbon dioxide molecules in the critical cluster are small in the case of large water amounts (up to 300 ppm) in the gas phase, but larger when there is very little water vapor (1 ppm).
authors.affiliation: Division of Atmospheric Sciences, Department of Physical Sciences, University of Helsinki, 00014 Helsinki, Finland. anni.maattanen@helsinki.fi
authors.forename: Anni
authors.initials: A
authors.lastname: Määttänen
authors.forename: Hanna
authors.initials: H
authors.lastname: Vehkamäki
authors.forename: Antti
authors.initials: A
authors.lastname: Lauri
authors.forename: Ismo
authors.initials: I
authors.lastname: Napari
authors.forename: Markku
authors.initials: M
authors.lastname: Kulmala