EXPERIMENTAL INVESTIGATION OF THE ORTHO/PARA RATIO OF NEWLY FORMED MOLECULAR HYDROGEN ON AMORPHOUS SOLID WATER
- LERMA, UMR 8112 du CNRS, de l'Observatoire de Paris et de l'Universite de Cergy Pontoise, 5 mail Gay Lussac, F-95000 Cergy Pontoise Cedex (France)
- Visiting Professor. Permanent address: Physics Department, Syracuse University, Syracuse, NY 13244-1320 (United States)
- Permanent address: LEPC Universite de Saida, BP138, ENSAR, 20002 Saida (Algeria)
Several astronomical observations have shown that the ortho/para ratio (OPR) of H{sub 2} can differ from the expected statistical value of 3 or the local thermodynamic equilibrium (LTE) value at the gas or dust temperature. It is thus important to know the OPR of H{sub 2} newly formed on dust grain surfaces, in order to clarify the dependence of the observed OPR in space on the formation process. Using an experimental setup designed to mimic interstellar medium environments, we measured the OPR of H{sub 2} and D{sub 2} formed on the surface of porous amorphous water ice held at 10 K. We report for the first time the OPR value for newly formed D{sub 2}, consistent with the expected LTE value at the high-temperature limit found by previous theoretical and experimental works on the determination of the OPR upon H{sub 2} formation on surfaces at low temperature.
- OSTI ID:
- 22086335
- Journal Information:
- Astrophysical Journal, Vol. 760, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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