Experimental studies of the dissociative recombination processes for the C₆D₆⁺ and C₆D₇⁺ ions

¹ Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden ;
e-mail: mathias.hamberg@physto.se
² Radboud University Nijmegen, Institute for Molecules and Materials, PO Box 9010, 6500 GL Nijmegen, The Netherlands
³ Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Rd., Lanzhou 730000, China
⁴ Department of Physics, Albert-Ludwigs Universität Freiburg, Hermann-Herder-Str. 3, 79104 Freiburg, Germany
⁵ Jan Kochanowski University, Świȩtokrzyska 15, 25406 Kielce, Poland
⁶ Manne Siegbahn Laboratory, Frescativägen 26, 114 18 Stockholm, Sweden

Abstract

We have investigated the dissociative recombination (DR) of the C₆D₆⁺ and C₆D₇⁺ ions using the CRYRING heavy-ion storage ring at Stockholm University, Sweden. The dissociative recombination branching ratios were determined at minimal collision energy, showing that the DR of both ions was dominated by pathways keeping the carbon atoms together in one product. The absolute reaction cross sections for the titular ions are best fitted by σ(E_cm [eV]) = 1.3 ± 0.4 × 10^-15 (E_cm [eV])^{−1.19 ± 0.02} cm² (C₆D₆⁺) and σ(E_cm [eV]) = 1.1 ± 0.3 ×  10^-15(E_cm [eV])^{−1.33 ± 0.02} cm² (C₆D₇⁺) in the intervals 3-300 meV and 3-200 meV respectively. The thermal rate constants of the titular reactions are best described by: k(T) = 1.3 ± 0.4 × 10^-6(T/300)^{−0.69 ± 0.02} cm³s^-1 for C₆D₆⁺ and k(T) = 2.0 ± 0.6 × 10^-6 (T/300)^{−0.83 ± 0.02} cm³s^-1 for C₆D₇⁺. These expressions correlates well with earlier flowing afterglow studies on the same process.