title: Rate coefficient of CN formation through radiative association: a theoretical study of quantum effects.
abstract: Radiative association of CN is simulated using a quantum dynamical as well as a semiclassical approach. A comparison of the resulting energy-resolved cross sections reveals striking quantum effects that are due to shape resonances. These, in turn, arise because of states that are quasibound by the centrifugal barrier. The quantal rate coefficient for temperatures from 40 to 1900 K has been computed using the Breit-Wigner theory to account for the resonances. Comparison with the results obtained by Singh and Andreazza [Astrophys. J. 537, 261 (2000)] shows that the semiclassical method, which completely omits the shape resonances, is accurate to within 25% above room temperature. At lower temperatures the contribution from the shape resonances to the radiative association rate is more significant.
authors.affiliation: Department of Chemistry, University of Gothenburg, SE-412 96 Gothenburg, Sweden. sergey.antipov@chem.gu.se
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Antipov
authors.forename: Tobias
authors.initials: T
authors.lastname: Sjölander
authors.forename: Gunnar
authors.initials: G
authors.lastname: Nyman
authors.forename: Magnus
authors.initials: M
authors.lastname: Gustafsson