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arXiv · 2008.03438

On the Encounter Desorption of Hydrogen Atoms on Ice Mantle

Qiang Chang·Xuli Zheng·Xia Zhang·Donghui Quan·Yang Lu·Qingkuan Meng·Xiaohu Li·Long-Fei Chen
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Abstract

At low temperatures (10 K), hydrogen atoms can diffuse quickly on grain ice mantles and frequently encounter hydrogen molecules, which cover a notable fraction of grain surface. The desorption energy of H atoms on H2 substrates is much less than that on water ice. The H atom encounter desorption mechanism is adopted to study the enhanced desorption of H atoms on H2 substrates. Using a small reaction network, we show that the steady-state surface H abundances predicted by the rate equation model that includes H atom encounter desorption agree reasonably well with the results from the more rigorous microscopic Monte Carlo method. For a full gas-grain model, H atom encounter desorption can reduce surface H abundances. Therefore, if a model adopts the encounter desorption of H atoms, it becomes more difficult for hydrogenation products such as methanol to form, but it is easier for C, O and N atoms to bond with each other on grain surfaces.

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Qiang Chang, Xuli Zheng, Xia Zhang, Donghui Quan, Yang Lu, Qingkuan Meng, Xiaohu Li, Long-Fei Chen. 2020-08-08. On the Encounter Desorption of Hydrogen Atoms on Ice Mantle. https://doi.org/10.1088/1674-4527/21/2/39

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