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Kinetic Monte Carlo simulations of the grain-surface back-diffusion effect

Published online by Cambridge University Press:  04 September 2018

Eric R. Willis Open the ORCID record for Eric R. Willis [Opens in a new window]  and
Robin T. Garrod
Eric R. Willis
Affiliation:
Department of Chemistry, University of Virginia Charlottesville, VA 22904-4319 email: [email protected]
Robin T. Garrod
Affiliation:
Department of Chemistry, University of Virginia Charlottesville, VA 22904-4319 email: [email protected] Department of Astronomy, University of Virginia Charlottesville, VA 22904-4325
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Abstract

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Back-diffusion is the phenomenon by which random walkers revisit binding sites on a lattice. This phenomenon must occur on interstellar dust particles, slowing down dust-grain reactions, but it is not accounted for by standard rate-equation models. Microscopic kinetic Monte Carlo models have been used to investigate the effect of back-diffusion on reaction rates on interstellar dust grains. Grain morphology, size, and grain-surface coverage were varied and the effects of these variations on the magnitude of the back-diffusion effect were studied for the simple H+H reaction system. This back-diffusion effect is seen to reduce reaction rates by a maximum factor of ∼5 for the canonical grain of 106 binding sites. The resulting data were fit to logarithmic functions that can be used to reproduce the effects of back-diffusion in rate-equation models.

Keywords

astrochemistryISM: moleculesmethods: numerical
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 13 , Symposium S332: Astrochemistry VII: Through the Cosmos from Galaxies to Planets , March 2017 , pp. 370 - 373
Copyright
Copyright © International Astronomical Union 2018 

References

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