Document Type

Article

Date

4-18-2007

Embargo Period

11-2012

Keywords

TBD

Language

English

Disciplines

Physics

Description/Abstract

Experimental results on the formation of molecular hydrogen on amorphous silicate surfaces are presented for the first time and analyzed using a rate equation model. The energy barriers for the relevant diffusion and desorption processes are obtained. They turn out to be significantly higher than those obtained earlier for polycrystalline silicates, demonstrating the importance of grain morphology. Using these barriers we evaluate the efficiency of molecular hydrogen formation on amorphous silicate grains under interstellar conditions. It is found that unlike polycrystalline silicates, amorphous silicate grains are efficient catalysts of H_{2} formation within a temperature range which is relevant to diffuse interstellar clouds. The results also indicate that the hydrogen molecules are thermalized with the surface and desorb with low kinetic energy. Thus, they are unlikely to occupy highly excited states.

Additional Information

5 pages, 3 figures, 1 table. Accepted to ApJL. Shortened a bit More information at http://arxiv.org/abs/astro-ph/0703248

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Source

Harvested from Arxiv.org

Creative Commons License

Creative Commons Attribution 3.0 License
This work is licensed under a Creative Commons Attribution 3.0 License.

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Physics Commons

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