===== On the Detection of the Butadiynyl Radical, C4H, in Extragalactic Sources =====

S. Muller, A. Beelen, M. Guélin, S. Aalto, J. H. Black, F. Combes, S. J. Curran, P. Theule, and S. N. Longmore\\
used the Australia Telescope Compact Array (ATCA) to study the molecular content of a foreground galaxy at //z// = 0.89 (FG0.89 consisting of two subsources, FG0.89SW and FG0.89NO) in absorption toward the quasar PKS 1830-211:\\
**[[https://doi.org/10.1051/0004-6361/201117096|Molecules at //z// = 0.89: A 4-mm-Rest-Frame Absorption-Line Survey toward PKS 1830-211]]**\\
//Astron. Astrophys.// **535**, (2011) Art. No. A103.\\
The linear butadiynyl radical, C<sub>4</sub>H, was identified by its //N// = 6 – 5 to 9 – 8 transitions with rest frequencies between 57.0 and 85.7 GHz. All transitions display fine structure splitting of about 40 MHz, whereas the H-hyperfine structure was not resolved. Even though the signal-to-noise ratio appears to be fairly good, it may be the cause of some relative intensity issue in the fine structure components of a respective rotational transition.


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Contributor(s): H. S. P. Müller; 5, 2012

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