Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C6H6
Benzonitrile as a Proxy for Benzene in the Cold ISM: Low-temperature Rate Coefficients for CN + C6H6
复制标题
DOI：
10.3847/2041-8213/ab7a9c
复制
发表时间：
2020-03-10
影响因子：
7.9
通讯作者：
Sims, Ian R.
中科院分区：
文献类型：
--
作者：
Cooke, Ilsa R.;Gupta, Divita;Sims, Ian R.
由于最近使用射电天文学在星际介质（ISM）中发现的第一个芳香分子苯腈被发现，CN和苯（C6H6）之间的低温反应引起了天体化学界的极大兴趣。苯是最简单的芳香分子之一，可能是多环芳烃的前体，苯腈被认为是苯的低温替代物。为了评估苯腈作为苯的替代品的稳健性，需要进行低温动力学测量，以确认在冷致密云中发现的低温下反应是否保持快速。在这里，我们研究了15-295 K温度范围内的C6H6 + CN反应，使用了公认的CRESU技术（法语缩写，代表均匀超音速流动反应动力学）结合脉冲激光光解-激光诱导荧光。我们得到的速率系数k(T)在（3.6-5.4）× 10(-10) cm(3) s（-1）范围内，在15 ~ 295 k之间没有明显的温度依赖性，证实了CN + C6H6反应在与冷ISM相关的温度下保持快速。
The low-temperature reaction between CN and benzene (C6H6) is of significant interest in the astrochemical community due to the recent detection of benzonitrile, the first aromatic molecule identified in the interstellar medium (ISM) using radio astronomy. Benzonitrile is suggested to be a low-temperature proxy for benzene, one of the simplest aromatic molecules, which may be a precursor to polycyclic aromatic hydrocarbons. In order to assess the robustness of benzonitrile as a proxy for benzene, low-temperature kinetics measurements are required to confirm whether the reaction remains rapid at the low gas temperatures found in cold dense clouds. Here, we study the C6H6 + CN reaction in the temperature range 15-295 K, using the well-established CRESU technique (a French acronym standing for Reaction Kinetics in Uniform Supersonic Flow) combined with pulsed-laser photolysis-laser-induced fluorescence. We obtain rate coefficients, k(T), in the range (3.6-5.4) x 10(-10) cm(3) s(-1) with no obvious temperature dependence between 15 and 295 K, confirming that the CN + C6H6 reaction remains rapid at temperatures relevant to the cold ISM.