Blázquez Sergio, González Daniel, Neeman Elias M, Ballesteros Bernabé, Agúndez Marcelino, Canosa André, Albaladejo José, Cernicharo José, Jiménez Elena
Departamento de Química Física, Facultad de Ciencias y Tecnologías Químicas, Universidad de Castilla-La Mancha, Avda. Camilo José Cela 1B, 13071, Ciudad Real, Spain.
Molecular Astrophysics Group, Instituto de Física Fundamental (IFF-CSIC), Consejo Superior de Investigaciones Científicas, C/Serrano 123, 28006, Madrid, Spain.
Phys Chem Chem Phys. 2020 Sep 23;22(36):20562-20572. doi: 10.1039/d0cp03203d.
Gas-phase reactions in the interstellar medium (ISM) are a source of molecules in this environment. The knowledge of the rate coefficient for neutral-neutral reactions as a function of temperature, k(T), is essential to improve astrochemical models. In this work, we have experimentally measured k(T) for the reaction between the OH radical and acetaldehyde, both present in many sources of the ISM. Laser techniques coupled to a CRESU system were used to perform the kinetic measurements. The obtained modified Arrhenius equation is k(T = 11.7-177.5 K) = (1.2 ± 0.2) × 10-11 (T/300 K)-(1.8±0.1) exp-{(28.7 ± 2.5)/T} cm3 molecule-1 s-1. The k(T) value of the title reaction has been measured for the first time below 60 K. No pressure dependence of k(T) was observed at ca. 21, 50, 64 and 106 K. Finally, a pure gas-phase model indicates that the title reaction could become the main CH3CO formation pathway in dark molecular clouds, assuming that CH3CO is the main reaction product at 10 K.
星际介质（ISM）中的气相反应是该环境中分子的一个来源。了解中性-中性反应的速率系数随温度的变化关系k(T)，对于改进天体化学模型至关重要。在这项工作中，我们通过实验测量了ISM中许多源都存在的OH自由基与乙醛之间反应的k(T)。结合CRESU系统的激光技术被用于进行动力学测量。得到的修正阿伦尼乌斯方程为k(T = 11.7 - 177.5 K) = (1.2 ± 0.2) × 10-11 (T/300 K)-(1.8±0.1) exp-{(28.7 ± 2.5)/T} cm3 molecule-1 s-1。首次在60 K以下测量了该标题反应的k(T)值。在约21、50、64和106 K时未观察到k(T)对压力的依赖性。最后，一个纯气相模型表明，假设CH3CO是10 K时的主要反应产物，该标题反应可能成为暗分子云中CH3CO形成的主要途径。
