2021MNRAS.503.2902M -
Mon. Not. R. Astron. Soc., 503, 2902-2912 (2021/May-2)
Collisional (de-)excitation of protonated cyanoacetylene (HC3NH+) by helium at low and moderate temperatures.
MOGREN AL MOGREN M., BEN ABDALLAH D., AL HARBI S.D.A., AL SALHI M.S. and HOCHLAF M.
Abstract (from CDS):
Protonated cyanoacetylene, HC3NH+, is detected in astrophysical media, where it plays a key role as an intermediate in the chemistries of HCN/HNC and of cyanopolyynes. We first generated a potential energy surface (PES) describing the intermonomer interaction between HC3NH+ and He in Jacobi coordinates using the highly correlated CCSD(T)-F12/aug-cc-pVTZ ab initio methodology. Then, scattering calculations based on an exact close-coupling quantum-scattering technique were done to obtain pure rotational cross-sections for the rotational (de-)excitation of HC3NH+ after collision with He for total energies up to 2500 cm–1. These cross-sections are used to deduce the collision rates in the 5-350 K temperature range for the low-lying rotational levels of HC3NH+ (up to j = 15). In addition, we generated an average PES for the HC3NH+-H2 system. The preliminary results show that the H2(jH2_ = 0) and He state-to-state de-excitation cross-sections have similar magnitudes, even though the H2 cross-sections are larger by a factor of 2-2.5. This work should help with the accurate derivation of protonated cyanoacetylene abundances in non-local thermodynamical equilibrium astrophysical media. These will put more constraints on the chemical pathways involving the formation and destruction of HC3NH+ while going back to the cyanopolyyne family and more generally those parts of nitrogen-containing molecular chemistry.
Abstract Copyright:
© 2021 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society
Journal keyword(s):
ISM: abundances
Simbad objects:
5
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