Hamberg Mathias, Kashperka Iryna, Thomas Richard D, Roueff Evelyne, Zhaunerchyk Vitali, Danielsson Mathias, af Ugglas Magnus, Österdah Fabian, Vigren Erik, Kaminska Magdalena, Källberg Anders, Simonsson Ansgar, Paal Andras, Gerin Maryvonne, Larsson Mats, Geppert Wolf D
Department of Physics, Stockholm University , Alba Nova, SE-106 91 Stockholm, Sweden.
J Phys Chem A. 2014 Aug 7;118(31):6034-49. doi: 10.1021/jp5032306. Epub 2014 Jul 24.
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.
利用合并离子 - 电子束方法，在瑞典斯德哥尔摩的重离子储存环CRYRING上对H(13)CO(+)的离解复合过程进行了研究。我们测量了碰撞能量约为0 eV时不同产物通道的分支比，结果如下：CO + H占87 ± 2%，OH + C占9 ± 2%，O + CH占4 ± 2%。还研究了主导反应通道中电子激发态CO的形成，我们报告了不同CO产物电子态的以下初步分支比：CO(X (1)Σ(+)) + H占54 ± 10%；CO(a (3)Π) + H占23 ± 4%；CO(a' (3)Σ(+)) + H占23 ± 4%。测量了约2 - 50000 meV之间的绝对截面，结果显示在3至15 eV之间存在共振结构。在与天体物理学相关的能量范围内（即1至300 meV之间）对截面进行了拟合，发现其符合表达式σ = 1.3 ± 0.3 × 10(-16) E(-1.29 ± 0.05) cm(2)，并确定相应的热速率常数为k(T) = 2.0 ± 0.4 × 10(-7)(T/300)(-0.79 ± 0.05) cm(3) s(-1)。使用IRAM 30米望远镜对红矩形天体进行的HCO(+)射电天文学观测，在该天体上1σ水平给出了HCO(+)的柱密度上限为4 × 10(11) cm(-2)，这表明之前关于HCO(+)的离解复合在该天体中发射观测到的卡梅伦带的激发态CO分子的产生中起重要作用的说法不成立。
