Molecular hydrogen formation on amorphous silicates under interstellar conditions

H. B. Perets*, A. Lederhendler, O. Biham, G. Vidali, L. Li, S. Sworos, E. Congiu, J. Roser, G. Manicó, J. R. Brucato, V. Pirronello

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

56 Scopus citations


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 H2 formation within a temperature range that 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.

Original languageAmerican English
Pages (from-to)L163-L166
JournalAstrophysical Journal
Issue number2 II
StatePublished - 1 Jun 2007


  • Dust, extinction
  • ISM: molecules
  • Molecular processes


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