论文标题
在TMC-1中发现环状C5H自由基
Discovery of the cyclic C5H radical in TMC-1
论文作者
论文摘要
在该空间中首次检测到Cyclic C5H（C-C5H），这是通过将乙基尼尔组CCH代替C-C3H自由基中的氢原子形成的自由基。 C-C5H物种是众所周知的线性自由基L-C5H的异构体，并且稳定6 kcal/mol。使用Yebes 40m射电望远镜在31.0-50.3 GHz范围内，TMC-1中的C-C5H物种总共检测到17种旋转转变。对于C-C5H，我们得出（9.0 +/- 0.9）E10 cm-2的色谱柱密度。此外，我们观察到L-C5H的12条线，并得出（1.3 +/- 0.3）E12 cm-2的柱密度，这导致丰度比C-C5H/L-C5H为0.069。这与模拟系统C-C3H/L-C3H的值形成鲜明对比，后者的比率为5.5。我们讨论了C-C5H的形成，并得出结论，这种自由基可能是在原子碳与二乙烯的反应中形成的。
Cyclic C5H (c-C5H), the radical formed by substituting an ethynyl group CCH for the hydrogen atom in the c-C3H radical, has been detected for the first time in the space. The c-C5H species is an isomer of the well-known linear radical l-C5H and is 6 kcal/mol less stable. A total of 17 rotational transitions were detected for the c-C5H species in TMC-1 within the 31.0-50.3 GHz range using the Yebes 40m radio telescope. We derive a column density of (9.0 +/- 0.9)e10 cm-2 for c-C5H. Additionally, we observed 12 lines for l-C5H and derive a column density for it of (1.3 +/- 0.3)e12 cm-2, which results in an abundance ratio c-C5H/l-C5H of 0.069. This is in sharp contrast with the value found for the analogue system c-C3H/l-C3H, whose ratio is 5.5 in TMC-1. We discuss the formation of c-C5H and conclude that this radical is probably formed in the reaction of atomic carbon with diacetylene.
