State-to-state rotational transition rates of the HCO+ ion by collisions with helium

Year: 2009

Authors: Buffa G., Dore L., Meuwly M.

Autors Affiliation: CNR, IPCF, I-56127 Pisa, Italy; Univ Bologna, Dipartimento Chim Ciamician, I-40136 Bologna, Italy; Dept Chem, CH-4056 Basel, Switzerland

Abstract: The rates of rotational transitions for HCO+, the most abundant ion in interstellar space, induced by collision with helium are obtained for temperatures ranging from 10 to 80 K. The calculations are based on a new potential energy surface for the He-HCO+ interaction and on a scattering matrix whose accuracy was checked by pressure broadening and shift measurements. The rates q(jj\’) decrease for increasing values of j and Delta j, with a temperature trend depending on the energy involved in the transitions: if it is small, the rates are almost constant, while an increase with T is found for other cases. Comparison with previous and less accurate results shows an agreement within 50 per cent. Comparison between state-to-state and pressure broadening cross-sections allows us to discuss importance and influence of elastic and inelastic collisions.

Journal/Review: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

Volume: 397 (4)      Pages from: 1909  to: 1914

More Information: MM acknowledges financial support from the Swiss National Science Foundation.
KeyWords: molecular data; ISM: molecules;
DOI: 10.1111/j.1365-2966.2009.14890.x

Citations: 25
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