Probing the H2 formation on the surface of grains in the laboratory, in connection with observations of H2 emission in the interstellar medium
Abstract
It is well-established that the gas-grain interaction plays an important role for the formation of molecules, in particular in the case of H2, whose abundance relative to H atoms in the ISM cannot be accounted for by gas-phase reactions. Whilst theoretical models of the gas-grain interaction have been recently developed, very few experimental studies of the processes involved have been performed to test their predictions. In particular data concerning the internal energy state of nascent H2 molecules are still scarce or conspicuously absent. These data relating to H2 are of fundamental importance with respect to the energy balance in the ISM. An experimental facility devoted to the study of molecular hydrogen formation on surfaces that mimics dust grains under physical conditions relevant to the interstellar medium is being developed in our laboratory. Our measurements will provide both internal energy and velocity distributions of the desorbed molecules. This work is of direct and fundamental interest for the understanding of H2 infrared observations in the ISM (dark clouds, Bok globules, star forming regions and molecular cloud in general) which are performed in collaboration in our group. The interpretation of such observations makes use of theoretical astrophysical models which include detailed chemical pathways and physical processes save data related to grain-surface processes which are only treated at the moment in a phenomenological way.
- Publication:
-
SF2A-2002: Semaine de l'Astrophysique Francaise
- Pub Date:
- June 2002
- Bibcode:
- 2002sf2a.conf...23B