Adsorption of H${}_2$ on Amorphous Solid Water Studied with Molecular Dynamics Simulations

Abstract

We investigated the behavior of H${}_2$, main constituent of the gas phase in dense clouds, after collision with amorphous solid water (ASW) surfaces, one of the most abundant chemical species of interstellar ices. We developed a general framework to study the adsorption dynamics of light species on interstellar ices. We provide binding energies and their distribution, sticking probabilities for incident energies between 1 meV and 60 meV, and thermal sticking coefficients between 10 and 300 K for surface temperatures from 10 to 110 K. We found that the sticking probability depends strongly on the adsorbate kinetic energy and the surface temperature, but hardly on the angle of incidence. We observed finite sticking probabilities above the thermal desorption temperature. Adsorption and thermal desorption should be considered as separate events with separate time scales. Laboratory results for these species have shown a gap in the trends attributed to the differently employed experimental techniques. Our results complement observations and extend them, increasing the range of gas temperatures under consideration. We plan to employ our method to study a variety of adsorbates, including radical and charged species.

arXiv commentQuantum-chemistry based study of the adsorption dynamics of H2 on amorphous solid water

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Cited by in corpus (8)

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• Enhanced formation of interstellar complex organic molecules on carbon monoxide ice
• Molecular Mobility of Extraterrestrial Ices: Surface Diffusion in Astrochemistry and Planetary Science
• Robust Binding Energy Distribution Sampling on Amorphous Solid Water Models. Method testing and validation with NH3, CO and CH4
• CO Adsorption Sites on Interstellar Water Ices Explored with Machine Learning Potentials. Binding energy distributions and snowline
• Investigating the impact of reactions of C and CH with molecular hydrogen on a glycine gas-grain network