Open AccessState‐to‐state rotational transition rates of the HCO + ion by collisions with helium
Author(s) -
Buffa G.,
Dore L.,
Meuwly M.
Publication year - 2009
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2009.14890.x
Subject(s) - physics , atomic physics , helium , ion , inelastic collision , helium 3 , helium 4 , rotational energy , scattering , isotopes of helium , nuclear physics , electron , quantum mechanics , optics
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 decrease for increasing values of j and Δ 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.