On the Detection of Pentadiynylidyne, C5H, in Space
The pentadiynylidyne radical in its 2Π1/2 lower spin component has been detected in six lines of three rotational transitions toward IRC +10216 by
J. Cernicharo, C. Kahane, J. Gómez-González; and M. Guélin,
Tentative Detection of the C<sub>5</sub>H Radical,
Astron. Astrophys. 164, L1–L4 (1986)
before it was actually detected in the laboratory.
Confirmation came also through the observation of four lines pertaining to the 2Π3/2 upper spin component in the 3 mm range for which the λ-doubling is just not resolvable:
J. Cernicharo, C. Kahane, J. Gómez-González; and M. Guélin,
Detection of the <sup>2</sup>Π<sub>3/2</sub> State of C<sub>5</sub>H,
Astron. Astrophys. 167, L5–L7 (1986).
Subsequently, it was also detected toward TMC-1 in one transition with resolved 1H hyperfine splitting as well as λ-doubling:
J. Cernicharo, M. Guélin, and C. M. Walmsley,
Detection of the Hyperfine Structure of the C<sub>5</sub>H Radical,
Astron. Astrophys. 172, L5–L6 (1987).
Contributor(s): H. S. P. Müller; 05, 2007