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- J. Cernicharo, M. Guelin, J. R. Pardo
"Detection of the linear radical HC4N in IRC+10216"
Astrophysical Journal, 615/2, L145-L148 (2004).
We report the detection of the linear radical HC4N in the
C-rich envelope of IRC +10216. After HCCN, HC4N is the second
member of the allenic chain family HC(2n)N observed in space.
The column density of HC4N is found to be
1.5*10**12 cm**(-2). The abundance ratio
HC2N/HC4N is 9, a factor of 2 larger than the
decrement observed for the cyanopolyynes
(HC(2n+1)N/HC(2n+3)N). Linear HC4N has a
3-Sigma electronic ground state and is one of the three
low-energy isomeric forms of this molecule. We have searched for the
bent and ringed HC4N isomers but could only derive an upper
limit to their column densities: 3*10**12 cm**(-2) (at 3 sigma).
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