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Research Interests: Gas-surface scattering

 

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We are currently working on the formation of H2 on graphite. H2 is the most abundant molecule in interstellar space and it plays an important role in the formation of stars and in interstellar chemistry through reactions with ions and radicals. Moreover, the energetics of the reaction directly influences 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. Therefore, we use graphite as a template.

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.

Our calculations are done in collaboration with Prof. A. J. Fisher of UCL and complement experiments done in the group of Prof. S. D. Price at UCL and astronomical modelling and observations done in the groups of Prof. D. A. Williams and Dr. J. Rawlings at UCL through the Centre for Cosmic Chemistry and Physics.

For more details, please see UCL Cosmic Dust Centre


Some recent references

  • Surface Coverage Effects on the formation of molecular hydrogen on graphite surfaces via an Eley-Rideal mechanism.
    Anthony J. H. M. Meijer, Andrew J. Fisher, and David C. Clary.
    J. Phys. Chem. A 107, 10862-10871 (2003).
    [PDF file on ACS web-site]
  • Formation excitation of H2
    Stephano Tine, David A. Williams, David C. Clary, Adam J. Farebrother, Andrew J. Fisher, and Anthony J. H. M. Meijer.
    Astrophys. Space Sci. 288, 377-389 (2003)
  • Isotope effects in the formation of molecular hydrogen on graphite surfaces via an Eley-Rideal mechanism.
    Anthony J. H. M. Meijer, Adam J. Farebrother, and David C. Clary.
    J. Phys. Chem. A, 106, 8996-9008 (2002).
    [PDF file on ACS web-site]
  • 3D time-dependent quantum mechanical calculations on the formation of molecular hydrogen via an Eley-Rideal mechanism
    Anthony J. H. M. Meijer, Adam J. Farebrother, David C. Clary, and Andrew J. Fisher.
    J. Phys. Chem. A, 105, 2173 (2001).
    [PDF file on ACS web-site]

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