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Deposition nucleation on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle

TitleDeposition nucleation on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle
Publication TypeJournal Article
Year of Publication2012
AuthorsWheeler, MJ, Bertram, AK
JournalAtmospheric Chemistry and Physics
Volume12
Start Page1189
Abstract

Deposition nucleation on two mineral species, kaolinite and illite, was studied using a flow cell coupled to an optical microscope. The results show that the S-ice conditions when ice first nucleated, defined as the onset S-ice (S-ice,S-onset), is a strong function of the surface area available for nucleation, varying from 100% to 125% at temperatures between 242 and 239 K. The surface area dependent data could not be described accurately using classical nucleation theory and the assumption of a single contact angle (defined here as the single-alpha model). These results suggest that caution should be applied when using contact angles determined from S-ice,S-onset data and the single-alpha model. In contrast to the single-alpha model, the active site model, the deterministic model, and a model with a distribution of contact angles fit the data within experimental uncertainties. Parameters from the fits to the data are presented.

DOI10.5194/acp-12-1189-2012