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