Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
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DOI：
10.1051/0004-6361/202244399
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发表时间：
2022-07-27
影响因子：
6.5
通讯作者：
de Vicente, P.
中科院分区：
文献类型：
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作者：
Cernicharo, J.;Fuentetaja, R.;de Vicente, P.
我们报道了用Quijote(1)线测量在TMC-1方向检测到富文烯(c-C5H4CCH2)。检测到K-a=0，1，2，3和J=9-15的30个转动跃迁。数据的最佳旋转温度拟合为9K，衍生柱密度为(2.7+/-0.3)×10(12)cm(-2)，仅比其潜在的前体环戊二烯(c-C5H6)低4.4倍，而比环戊二烯的乙炔衍生物高1.4-1.9倍。我们搜索了富烯(c-C5H4CH2)，这是一种环戊二烯的CH2衍生物，我们得到了它的柱密度的3西格玛上限为(3.5+/-0.5)×10(12)cm(-2)。苯的甲基和乙烯基衍生物甲苯(C6H5CH3)和苯乙烯(C6H5C2H3)的上限也得到了测定。环戊二烯(c-C5H6)与乙炔基自由基(CCH)反应可能生成富烯和乙炔基环戊二烯。然而，TMC-1中循环的自下而上的气相合成将环戊二烯的丰度低估了两个数量级，这加强了研究在寒冷的暗云环境中循环的所有可能的化学路径的必要性，例如TMC-1。然而，C3H3+和C2H4之间的反应在模型和观测丰度之间产生了很好的一致性。
We report the detection of fulvenallene (c-C5H4CCH2) in the direction of TMC-1 with the QUIJOTE(1) line survey. Thirty rotational transitions with K-a = 0,1,2,3 and J = 9-15 were detected. The best rotational temperature fitting of the data is 9 K and a derived column density is (2.7 +/- 0.3) x 10(12) cm(-2), which is only a factor of 4.4 below that of its potential precursor cyclopentadiene (c-C5H6), and 1.4-1.9 times higher than that of the ethynyl derivatives of cyclopentadiene. We searched for fulvene (c-C5H4CH2), a CH2 derivative of cyclopentadiene, for which we derive a 3 sigma upper limit to its column density of (3.5 +/- 0.5) x 10(12) cm(-2). Upper limits were also obtained for toluene (C6H5CH3) and styrene (C6H5C2H3), the methyl and vinyl derivatives of benzene. Fulvenallene and ethynyl cyclopentadiene are likely formed in the reaction between cyclopentadiene (c-C5H6) and the ehtynyl radical (CCH). However, the bottom-up gas-phase synthesis of cycles in TMC-1 underestimates the abundance of cyclopentadiene by two orders of magnitude, which strengthens the need to study all possible chemical pathways to cyclisation in cold dark cloud environments, such as TMC-1. However, the inclusion of the reaction between C3H3+ and C2H4 produces a good agreement between model and observed abundances.