Dissociative Recombination of Nitrile Ions: DCCCN+ and DCCCND

• Published in: The Astrophysical journal 2004-10, Vol.613 (2), p.1302-1309
• Main Authors: Geppert, W. D, Ehlerding, A, Hellberg, F, Semaniak, J, Österdahl, F, Kamińska, M, Al-Khalili, A, Zhaunerchyk, V, Thomas, R, af Ugglas, M, Källberg, A, Simonsson, A, Larsson, M
• Format: Article
• Language: English
• Subjects: astrochemistry; Astronomy; Atomic and molecular data, spectra, and spectral parameters (opacities, rotation constants, line identification, oscillator strengths, gf values, transition probabilities, etc.); Atomic, molecular, chemical, and grain processes; Earth, ocean, space; Exact sciences and technology; Fundamental aspects of astrophysics; Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations; Interstellar medium (ism) and nebulae in milky way; methods : laboratory; molecular data; Stellar systems. Galactic and extragalactic objects and systems. The universe
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.1086/422335

Branching ratios and absolute cross sections have been measured for the dissociative recombination of DCCCN+ and DCCCND+ using the CRYRING ion storage ring. In the case of DCCCN+ the dissociation yielding D + C3N and those leading to two fragments containing a pair of heavy atoms dominate, whereas pathways producing a fragment with three heavy atoms play only a minor role. Conversely, for DCCCND+, only those channels preserving the carbon chain or producing two fragments with a pair of heavy atoms each are detected. The cross sections of the reactions are very similar and can be fitted to the expressions sigma = (2.9 +/- 0.5) x 10(-15)E(eV)(-1.05 +/- 0.02) cm(2) and sigma = (2.3 +/- 0.4) x 10(-15)E(eV)(-1.10 +/- 0.02) cm(2) for DCCCN+ and DCCCND+, respectively. From these data, thermal reaction rates of k(T) = (1.5 +/- 0.3) x 10(-6)(T/300 K)(-0.60 +/- 0.02) cm(3) s(-1) and k(T) = (1.5 +/- 0.3) x 10(-6)(T/300 K)(-0.58 +/- 0.02) cm(3) s(-1) were calculated for DCCCN+ and DCCCND+, respectively. These rates and branching ratios are compared with those hitherto used in astrophysical models.