Sleiman Chantal, El Dib Gisèle, Rosi Marzio, Skouteris Dimitrios, Balucani Nadia, Canosa André
Institut de Physique de Rennes, UMR 6251 du CNRS - Université de Rennes 1, Bat. 11C, Campus de Beaulieu, 263 Avenue du Général Leclerc, F-35042 Rennes Cedex, France.
Phys Chem Chem Phys. 2018 Feb 21;20(8):5478-5489. doi: 10.1039/c7cp05746f.
The reaction between cyano radicals (which are ubiquitous in interstellar clouds) and methylamine (a molecule detected in various interstellar sources) has been investigated in a synergistic experimental and theoretical study. The reaction has been found to be very fast in the entire range of temperatures investigated (23-297 K) by using a CRESU apparatus coupled to pulsed laser photolysis - laser induced fluorescence. The global experimental rate coefficient is given by In addition, dedicated electronic structure calculations of the underlying potential energy surface have been performed, together with capture theory and RRKM calculations. The experimental data have been interpreted in the light of the theoretical calculations and the product branching ratio has been established. According to the present study, in the range of temperatures investigated the title reaction is an efficient interstellar route of formation of cyanamide, NHCN, another interstellar species. The second most important channel is the one leading to methyl cyanamide, CHNHCN (an isomer of aminoacetonitrile), via a CN/H exchange mechanism with a yield of 12% of the global reaction in the entire range of temperatures explored. For a possible inclusion in future astrochemical models we suggest, by referring to the usual expression the following values: α = 3.68 × 10 cm molec s, β = -1.80, γ = 7.79 K for the channel leading to NHCN + CH; α = 5.05 × 10 cm molec s, β = -1.82, γ = 7.93 K for the channel leading to CHNHCN + H.
在一项协同的实验和理论研究中，对氰基自由基（在星际云中普遍存在）与甲胺（在各种星际源中检测到的一种分子）之间的反应进行了研究。通过使用与脉冲激光光解 - 激光诱导荧光联用的CRESU装置，发现在所研究的整个温度范围（23 - 297 K）内该反应非常迅速。此外，还进行了相关势能面的专门电子结构计算，以及捕获理论和RRKM计算。根据理论计算对实验数据进行了解释，并确定了产物分支比。根据本研究，在所研究的温度范围内，标题反应是形成氰胺（NHCN，另一种星际物种）的有效星际途径。第二重要的通道是通过CN/H交换机制生成甲基氰胺（CHNHCN，氨基乙腈的异构体）的通道，在整个探索的温度范围内，其产率为总反应的12%。为了可能纳入未来的天体化学模型，我们参考通常的表达式建议以下值：对于生成NHCN + CH的通道，α = 3.68 × 10 cm³ molec⁻¹ s⁻¹，β = -1.80，γ = 7.79 K；对于生成CHNHCN + H的通道，α = 5.05 × 10 cm³ molec⁻¹ s⁻¹，β = -1.82，γ = 7.93 K。
