title: Spin-orbit quenching of the C+(2P) ion by collisions with para- and ortho-H2.
abstract: Spin-orbit (de-)excitation of C(+)((2)P) by collisions with H2, a key process for astrochemistry, is investigated. Quantum-mechanical calculations of collisions between C(+) ions and para- and ortho-H2 have been performed in order to determine the cross section for the C(+) (2)P3∕2 → (2)P1∕2 fine-structure transition at low and intermediate energies. The calculation are based on new ab initio potential energy surfaces obtained using the multireference configuration interaction method. Corresponding rate coefficients were obtained for temperatures ranging from 5 to 500 K. These rate coefficients are compared to previous estimations, and their impact is assessed through radiative transfer computation. They are found to increase the flux of the (2)P3∕2 → (2)P1∕2 line at 158 μm by up to 30% for typical diffuse interstellar cloud conditions.
authors.affiliation: LOMC - UMR 6294, CNRS-Université du Havre, 25, Rue Philippe Lebon, BP 540, 76058 Le Havre, France. francois.lique@univ-lehavre.fr
authors.forename: François
authors.initials: F
authors.lastname: Lique
authors.forename: Ghofran
authors.initials: G
authors.lastname: Werfelli
authors.forename: Philippe
authors.initials: P
authors.lastname: Halvick
authors.forename: Thierry
authors.initials: T
authors.lastname: Stoecklin
authors.forename: Alexandre
authors.initials: A
authors.lastname: Faure
authors.forename: Laurent
authors.initials: L
authors.lastname: Wiesenfeld
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Dagdigian
mesh_terms: D002244:Carbon / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D011789:Quantum Theory
chemical_list: D007477:Ions; D002244:Carbon; D006859:Hydrogen