论文标题
星际硝酸阴离子：在TMC-1中检测C3N-和C5N-
Interstellar nitrile anions: Detection of C3N- and C5N- in TMC-1
论文作者
论文摘要
我们使用Yebes 40 m望远镜向金牛座地区的冷深核TMC-1报告了C3N和C5N-的首次检测。观察到的C3N/C3N和C5N/C5N-丰度比分别为140和2。这与富含碳富含碳的恒星IRC+10216的折叠式包膜相似。尽管中性的形成机制在恒星（离子中性反应）和折叠云（光电解离和自由基反应）中是不同的，但C3N/C3N/C3N/C5N/C5N-含量比的相似性强烈暗示了这些沉积物中常见的化学途径。我们讨论了辐射电子附着，N原子和碳链阴离子CN-之间的反应以及与HC3N和HC5N的H-反应的作用，作为形成CNN-的可能路线。 TMC-1中C5N-的检测为分配给该阴离子的线条提供了强有力的支持，因为它排除了金属含有物种或振动激发态的可能性。对于C5N-和中性自由基C5N，已在TMC-1中观察到的频率和IRC+10216中观察到的频率得出了新的旋转参数。
We report on the first detection of C3N- and C5N- towards the cold dark core TMC-1 in the Taurus region, using the Yebes 40 m telescope. The observed C3N/C3N- and C5N/C5N- abundance ratios are 140 and 2, respectively; that is similar to those found in the circumstellar envelope of the carbon-rich star IRC+10216. Although the formation mechanisms for the neutrals are different in interstellar (ion-neutral reactions) and circumstellar clouds (photodissociation and radical-neutral reactions), the similarity of the C3N/C3N- and C5N/C5N- abundance ratios strongly suggests a common chemical path for the formation of these anions in interstellar and circumstellar clouds. We discuss the role of radiative electronic attachment, reactions between N atoms and carbon chain anions Cn-, and that of H- reactions with HC3N and HC5N as possible routes to form CnN-. The detection of C5N- in TMC-1 gives strong support for assigning to this anion the lines found in IRC+10216, as it excludes the possibility of a metal-bearing species, or a vibrationally excited state. New sets of rotational parameters have been derived from the observed frequencies in TMC-1 and IRC+10216 for C5N- and the neutral radical C5N.
