Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, Colorado 80309-0389, USA.
Astrobiology. 2009 Dec;9(10):1001-5. doi: 10.1089/ast.2008.0277.
The recent discovery of molecular negative ions in the interstellar medium suggests that these species may be reactive intermediates in astrochemical processes. Our recent studies indicate that these anions, despite their high electron binding energies, are reactive with atomic reagents. In this work, we report that two species of interstellar interest, glycine (NH(2)CH(2)COOH) and cyanoacetylene (HC(3)N), can be readily formed by associative detachment of their corresponding deprotonated anions with hydrogen atoms. The reaction rate constants for glycine anion (NH(2)CH(2)CO(2)(-)) and cyanoacetylene anion (C(3)N(-)) with H atom have been measured to be 2.0 +/- 0.5 x10(-10) cm(3) s(-1) and 5.4 +/- 0.2 x 10(-10) cm(3) s(-1), respectively, where the error bars represent one standard deviation of the mean; the estimated total error is +/- 50%. A possible reaction mechanism for chemical conversion of species observed in the interstellar medium is also described.
星际介质中分子负离子的最近发现表明，这些物种可能是天体化学过程中的反应中间体。我们最近的研究表明，尽管这些阴离子具有高电子结合能，但它们与原子试剂反应。在这项工作中，我们报告说，两种星际感兴趣的物种，甘氨酸（NH(2)CH(2)COOH）和氰基乙炔（HC(3)N），可以通过它们相应的去质子化阴离子与氢原子的缔合脱附容易地形成。甘氨酸阴离子（NH(2)CH(2)CO(2)(-))和氰基乙炔阴离子（C(3)N(-))与 H 原子的反应速率常数分别测量为 2.0 +/- 0.5 x10(-10) cm(3) s(-1)和 5.4 +/- 0.2 x 10(-10) cm(3) s(-1)，其中误差条代表平均值的一个标准差；估计的总误差为 +/- 50%。还描述了一种可能的星际介质中观察到的物种化学转化的反应机制。
