Document Type

Article

Date

11-21-2008

Keywords

TBD

Language

English

Disciplines

Physics

Description/Abstract

The study of the formation of molecular hydrogen on low temperature surfaces is of interest both because it allows to explore elementary steps in the heterogeneous catalysis of a simple molecule and because of the applications in astrochemistry. Here we report results of experiments of molecular hydrogen formation on amorphous silicate surfaces using temperature-programmed desorption (TPD). In these experiments beams of H and D atoms are irradiated on the surface of an amorphous silicate sample. The desorption rate of HD molecules is monitored using a mass spectrometer during a subsequent TPD run. The results are analyzed using rate equations and the activation energies of the processes leading to molecular hydrogen formation are obtained from the TPD data. We show that a model based on a single isotope provides the correct results for the activation energies for diffusion and desorption of H atoms. These results can thus be used to evaluate the formation rate of H_2 on dust grains under the actual conditions present in interstellar clouds.

Additional Information

30 pages, 1 table, 6 figures. Published version More information at http://arxiv.org/abs/0708.1647

Authors listed are from Syracuse University. For additional authors, click "Download."

Source

Harvested from Arxiv.org

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

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