Stochastic effects in H2SO4-H2O cluster growth

Christoph Köhn*, Martin Bødker Enghoff, Henrik Svensmark

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The nucleation of sulfuric acid-water clusters plays a significant role in the formation of aerosols. Based on a recently developed particle Monte Carlo (MC) Code, we analyze how the growth of sulfuric acid-water clusters is influenced by stochastic fluctuations. We here consider samples of H2SO4-H2O clusters at T = 200 K with a relative humidity of 50%, with particle concentrations between 105 and 107 cm–3 in volumes between 10-6 and 10-2 cm3. We present the temporal evolution of the formation rate and of the size distribution as well as growth rates and the onset time of the nucleation above a given cluster size with and without constant production of new monomers. Clear evidence is revealed by the MC code that fluctuations result in a faster growth rate of the smallest clusters compared to deterministic continuum models that do not contain the stochastic effects. The faster growth of small clusters in turn influences the growth of larger clusters. Depending on the volume size, the onset time for clusters larger than 0.85 nm varies between 1000 s and 20,000 s for n=105 cm–3 and between 10 s and 100 s for n=107 cm–3.
Original languageEnglish
JournalAerosol Science and Technology
Volume54
Issue number9
Pages (from-to)1007-1018
ISSN0278-6826
DOIs
Publication statusPublished - 2020

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