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arXiv · 1711.03171

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

Eric R. Willis·Robin T. Garrod
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Abstract

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 10$^6$ 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.

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Eric R. Willis, Robin T. Garrod. 2017-11-08. Kinetic Monte Carlo simulations of the grain-surface back-diffusion effect. https://doi.org/10.1017/s1743921317007633

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