===== On the Detection of Hexatriynyl, C6H, in Space ===== The hexatriynyl radical in its ²Π_3/2 lower spin component has been detected toward TMC-1 by\\ H. Suzuki, M. Ohishi, N. Kaifu, S.-I. Ishikawa, and T. Kasuga,\\ **[[https://ui.adsabs.harvard.edu/abs/1986PASJ...38..911S|Detection of the Interstellar C₆H Radical]]**,\\ //Publ. Astron. Soc. Japan// **38** 911–917 (1986) and\\ **[[https://ui.adsabs.harvard.edu/abs/1987PASJ...39..193S|Detection of C₆H in the ²Π_1/2 State toward IRC +10216]]** by\\ S. Saito, K. Kawaguchi, H. Suzuki, M. Ohishi, N. Kaifu, and S.-I. Ishikawa,\\ //Publ. Astron. Soc. Japan// **39** 193–199 (1987)\\ before it was actually detected in the laboratory. Transitions of the lowest excited //v//₁₁ = 1 vibrational state have been identified very recently:\\ J. Cernicharo, M. Guélin, M. Agúndez, M. C. McCarthy, and P. Thaddeus,\\ **[[https://doi.org/10.1086/595583|Detection of C₅N^– and Vibrationally Excited C₆H in IRC +10216]]**\\ //Astrophys. J.// **688** L83–L86 (2008).\\ The Renner-Teller interaction causes this state to split into three components: ²Σ^–, ²Δ with spin-orbit splitting, and ²Σ⁺. The lowest ²Σ^– state as well as both spin-components of the ²Δ state were detected. The ²Σ⁺ was not seen; it is probably overlapped by the lower ²Σ^– state and possibly too weak to be recognized. ---- Contributor(s): H. S. P. Müller; 11, 2006; 10, 2008 ----