Other
Scientific paper
May 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011iaus..280p.228l&link_type=abstract
The Molecular Universe, Posters from the proceedings of the 280th Symposium of the International Astronomical Union held in Tole
Other
Scientific paper
Using the CRESU (Reaction Kinetics in Uniform Supersonic Flow) technique, the kinetics of a hundred of chemical reactions has been studied in our group during the last 15 years. The low temperatures (down to 6 K) achieved in these experiments allow us to provide valuable input to photochemical models of planetary atmospheres and interstellar clouds. Hydrogen predominates in the interstellar medium and in many planetary atmospheres. From a chemical point of view however, atom-H_2 reactions are in most of the cases endothermic, unless the atom involved is in an electronically excited state or in some specific cases where the hydride (atom-H) formed during the reaction has a dissociation energy greater than the dissociation energy of H_2 (4.48 eV). We report here two kinetics studies at temperatures as low as 6 K for reactions of sulphur atom in its first electronically excited state, S(^1D), and fluorine atom in its ground state, F(^2P), with H_2: Rate coefficients have been measured for the reaction S(^1D) + H_2 down to 5.8 K, a new record for neutral-neutral reactions. This reaction could play a key role in interstellar sulfur chemistry in dense regions such as protoplanetary disks. The kinetics results will be compared to the results of crossed beam dynamics at very low collision and with quantum theoretical calculations. Fluorine is the only atom that, in its ground state, can react exothermically with H_2. Theoretical models for the interstellar chemistry corroborated by recent observations have predicted that hydrogen fluoride will be the dominant reservoir of gas phase fluorine over a wide range of conditions as the result of the reaction F(^2P) +H_2 → HF + F. This makes of HF an excellent candidate for tracing H_2 in the ISM. From a theoretical point of view, this reaction has long served as a benchmark for comparison between experiments and quantum scattering calculations. Experiments are underway employing the PLP-LIF technique with VUV LIF detection of the H atom product of the reaction in the temperature range 5-20 K. We will present our latest results on this important reaction.
Berteloite Coralie
Canosa André
Le Picard Sébastien D.
Sims Ian R.
Tizniti M.
No associations
LandOfFree
Atom - H_2 reactions at very low temperatures and astrophysical implications does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Atom - H_2 reactions at very low temperatures and astrophysical implications, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Atom - H_2 reactions at very low temperatures and astrophysical implications will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-929785