H2is one of the most important molecules in the interstellar medium. It plays a pivotal role in interstellar chemistry through reactions with ions and radicals. Furthermore, the energetics of the H2 formation reaction directly affect the thermal balance of the interstellar medium. It is widely accepted that the dominant mechanism for the formation of H2 in interstellar clouds is through surface-catalysed reactions on dust-grains, since alternative reaction mechanism cannot account for the abundance of hydrogen molecules in the interstellar medium, especially in molecular clouds. The precise nature of these dust grains is not known, but there is observational evidence that they are (part) carboneceous.
To investigate the formation of H2 in the interstellar medium, we perform time-dependent quantum mechanical calculations on the H2 formation on graphite through the Eley-Rideal mechanism under conditions that are relevant for the ISM. We calculate the probabilities of producing H2 in particular rotational and vibrational states.
The calculations are being done to complement experiments currently being done in the Centre for Cosmic Chemistry and Physics.
Adam J. Farebrother, Anthony J. H. M. Meijer, David C. Clary and Andrew J Fisher, Chem. Phys. Lett. 319, 303 (2000).
David A. Williams, David E. Williams, David C. Clary, Adam Farebrother, Andrew Fisher, Jon Gingell, Richard Jackman, Nigel Mason, Anthony J. H. M. Meijer, James Perry, Steven Price, and Jonathan Rawlings in ``Molecular Hydrogen in space''F. Combes and G. Pineau des Forets (Eds.) (Cambridge University Press, 2000), in press.
Anthony J. H. M. Meijer, Adam J. Farebrother, and David C. Clary, J. Phys. Chem. A, submitted.