Even the octatetraynyl radical in its 2Π3/2 lower spin component has been detected in ten rotational transitions toward IRC +10216 by
J. Cernicharo, and M. Guélin,
Discovery of the C<sub>8</sub>H Radical,
Astron. Astrophys. 309 L27–L30 (1996)
before it was actually detected in the laboratory.
Later, it was also identified in TMC-1 by observing four lines of two rotational transitions:
M. B. Bell, P. A. Feldman, J. K. G. Watson, M. C. McCarthy, M. J. Travers, C. A. Gottlieb, and P. Thaddeus,
Observations of Long C<sub>n</sub>H Molecules in the Dust Cloud TMC-1,
Astrophys. J. 518 740–747 (1999).
Contributor(s): H. S. P. Müller; 05, 2007