title: Collisional excitation of interstellar cyclopropenylidene.
abstract: Theoretical rotational excitation rates were computed for C3H2 in collisions with He atoms at temperatures from 30 to 120 K.  The intermolecular forces were obtained from accurate self-consistent field and perturbation theory calculations, and collision dynamics were treated within the infinite-order sudden approximation.  The accuracy of the latter was examined by comparing with the more exact coupled states approximation.
authors.affiliation: NASA/Goddard Space Flight Center, Institute for Space Studies, New York, USA.
authors.forename: S
authors.initials: S
authors.lastname: Green
authors.forename: D J
authors.initials: DJ
authors.lastname: DeFrees
authors.forename: A D
authors.initials: AD
authors.lastname: McLean
mesh_terms: D055580:Astronomical Phenomena; D001256:Astronomy; D019471:Elementary Particle Interactions; D005118:Extraterrestrial Environment; D006371:Helium / Q000032:analysis / Q000737:chemistry*; D006844:Hydrocarbons, Cyclic / Q000032:analysis / Q000737:chemistry*; D008958:Models, Molecular; D016082:Solar System; D013696:Temperature
chemical_list: D006844:Hydrocarbons, Cyclic; D006371:Helium