title: Experimental studies of H13CO+ recombining with electrons at energies between 2-50,000 meV.
abstract: An investigation into the dissociative recombination process for H(13)CO(+) using merged ion-electron beam methods has been performed at the heavy ion storage ring CRYRING, Stockholm, Sweden. We have measured the branching fractions of the different product channels at ∼ 0 eV collision energy to be the following: CO + H 87 ± 2%, OH + C 9 ± 2%, and O + CH 4 ± 2%. The formation of electronically excited CO in the dominant reaction channel has also been studied, and we report the following tentative branching fractions for the different CO product electronic states: CO(X (1)Σ(+)) + H, 54 ± 10%; CO(a (3)Π) + H, 23 ± 4%; and CO(a' (3)Σ(+)) + H, 23 ± 4%. The absolute cross section between ∼ 2-50 000 meV was measured and showed resonance structures between 3 and 15 eV. The cross section was fitted in the energy range relevant to astrophysics, i.e., between 1 and 300 meV, and was found to follow the expression σ = 1.3 ± 0.3 × 10(-16) E(-1.29 ± 0.05) cm(2) and the corresponding thermal rate constant was determined to be k(T) = 2.0 ± 0.4 × 10(-7)(T/300)(-0.79 ± 0.05) cm(3) s(-1). Radioastronomical observations with the IRAM 30 m telescope of HCO(+) toward the Red Rectangle yielded an upper column density limit of 4 × 10(11) cm(-2) of HCO(+) at the 1σ level in that object, indicating that previous claims that the dissociative recombination of HCO(+) plays an important role in the production of excited CO molecules emitting the observed Cameron bands in that object are not supported.
authors.affiliation: Department of Physics, Stockholm University , Alba Nova, SE-106 91 Stockholm, Sweden.
authors.forename: Mathias
authors.initials: M
authors.lastname: Hamberg
authors.forename: Iryna
authors.initials: I
authors.lastname: Kashperka
authors.forename: Richard D
authors.initials: RD
authors.lastname: Thomas
authors.forename: Evelyne
authors.initials: E
authors.lastname: Roueff
authors.forename: Vitali
authors.initials: V
authors.lastname: Zhaunerchyk
authors.forename: Mathias
authors.initials: M
authors.lastname: Danielsson
authors.forename: Magnus
authors.initials: M
authors.lastname: af Ugglas
authors.forename: Fabian
authors.initials: F
authors.lastname: Österdah
authors.forename: Erik
authors.initials: E
authors.lastname: Vigren
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kaminska
authors.forename: Anders
authors.initials: A
authors.lastname: Källberg
authors.forename: Ansgar
authors.initials: A
authors.lastname: Simonsson
authors.forename: Andras
authors.initials: A
authors.lastname: Paal
authors.forename: Maryvonne
authors.initials: M
authors.lastname: Gerin
authors.forename: Mats
authors.initials: M
authors.lastname: Larsson
authors.forename: Wolf D
authors.initials: WD
authors.lastname: Geppert