Nuclear spin conversion of molecular hydrogen on amorphous solid water in the presence of O2traces
| Autor: | X. Michaut, H. Mokrane, Jean-Louis Lemaire, J. H. Fillion, François Dulieu, H. Chaabouni, E. Congiu, M. Chehrouri, E. Matar |
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| Rok vydání: | 2011 |
| Předmět: |
Resonance-enhanced multiphoton ionization
Chemistry Thermal desorption spectroscopy Diffusion Hydrogen molecule Analytical chemistry General Physics and Astronomy chemistry.chemical_element 01 natural sciences 7. Clean energy Oxygen Amorphous solid Interstellar medium 13. Climate action 0103 physical sciences Physical and Theoretical Chemistry 010306 general physics Spectroscopy 010303 astronomy & astrophysics |
| Zdroj: | Phys. Chem. Chem. Phys.. 13:2172-2178 |
| ISSN: | 1463-9084 1463-9076 |
| Popis: | Nuclear spin conversion (NSC) of ortho- to para-H(2) and para- to ortho-D(2) has been investigated on an amorphous solid water (ASW) surface at 10 K, in the presence of co-adsorbed O(2). The dynamics of the nuclear spin conversion could be revealed by combination of resonance enhanced multiphoton ionization spectroscopy (REMPI) with temperature programmed desorption (TPD) experiments. The conversion rates are consistent with a diffusion of molecular hydrogen inducing a nuclear spin conversion enhanced in the vicinity of molecular oxygen. The conversion times were found to increase with decreasing O(2) and H(2) coverage. Finally, on oxygen free ASW surface, the extremely long conversion characteristic times measured showed that such surface is not an efficient catalyst for NSC, in contradiction with hypothesis commonly made for interstellar medium. |
| Databáze: | OpenAIRE |
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