星际异氰原（CNCN）的发现：二氰基多炔在太空中丰富的进一步证据
Discovery of interstellar isocyanogen (CNCN): further evidence that dicyanopolyynes are abundant in space
摘要：
人们认为，二氰基多炔可能是潜在的丰富的星际分子，虽然它们缺乏偶极矩，使其不可能通过射电天文学技术检测到它们。最近，这个化学家族中最简单的成员氰（NCCN）首次在星际空间中通过探测其质子化形式对稠密的云层L483和TMC-1进行了间接探测。在这里，我们提出了第二个坚定的证据NCCN在星际空间中的存在，即检测的亚稳态和极性异构体异氰（CNCN）。这个物种已经在L483中被发现，并在TMC-1中通过使用IRAM 30米望远镜在3毫米波段观察各种旋转跃迁而被初步确定。我们推导出L483中CNCN的束平均柱密度为1.6e12 cm-2，TMC-1中为9 e11 cm-2，这意味着相对于H2的丰度在（5-9）e-11范围内。虽然NCCN在星际云中的存在似乎是毫无疑问的，由于NCCNH+和CNCN的检测，对其丰度的严格限制仍然受到NCCN与NCCNH+，特别是与CNCN的化学联系的知识不足的阻碍。我们估计NCCN可能相当丰富，相对于H2在1 e-9 - 1 e-7的范围内，如其他丰富的腈如HCN和HC 3 N。
英文摘要：
It is thought that dicyanopolyynes could be potentially abundant interstellar molecules, although their lack of dipole moment makes it impossible to detect them through radioastronomical techniques. Recently, the simplest member of this chemical family, cyanogen (NCCN), was indirectly probed for the first time in interstellar space through the detection of its protonated form toward the dense clouds L483 and TMC-1. Here we present a second firm evidence of the presence of NCCN in interstellar space, namely the detection of the metastable and polar isomer isocyanogen (CNCN). This species has been identified in L483 and tentatively in TMC-1 by observing various rotational transitions in the 3 mm band with the IRAM 30m telescope. We derive beam-averaged column densities for CNCN of 1.6e12 cm-2 in L483 and 9e11 cm-2 in TMC-1, which imply fractional abundances relative to H2 in the range (5-9)e-11. While the presence of NCCN in interstellar clouds seems out of doubt owing to the detection of NCCNH+ and CNCN, putting tight constraints on its abundance is still hampered by the poor knowledge of the chemistry that links NCCN with NCCNH+ and especially with CNCN. We estimate that NCCN could be fairly abundant, in the range 1e-9 - 1e-7 relative to H2, as other abundant nitriles like HCN and HC3N.
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