@article{1538-4357-480-1-L63,
  author={W. D. Langer and T. Velusamy and T. B. H. Kuiper and R. Peng and M. C. McCarthy and M. J. Travers and A. Kovács and C. A.
Gottlieb and P. Thaddeus},
  title={First Astronomical Detection of the Cumulene Carbon Chain Molecule H2C6 in TMC-1},
  journal={The Astrophysical Journal Letters},
  volume={480},
  number={1},
  pages={L63},
  url={http://stacks.iop.org/1538-4357/480/i=1/a=L63},
  year={1997},
  abstract={The cumulene carbenes are important components of hydrocarbon chemistry in low-mass star-forming cores. Here we report the first astronomical detection of the long-chain cumulene carbene H 2 C 6 in the interstellar cloud TMC-1, from observations of two of its rotational transitions: J K, K' = 7 1,7 → 6 1,6 at 18.8 GHz and 8 1,8 → 7 1,7 at 21.5 GHz, using NASA's Deep Space Network 70 m antenna at Goldstone, California. In addition we also observed the shorter cumulene carbene H 2 C 4 at the same position. The fractional abundance of H 2 C 6 relative to H 2 is about 4.7 × 10 -11 and that of H 2 C 4 is about 1.1 × 10 -9 . The abundance of H 2 C 6 is in fairly good agreement with gas-phase chemical models for young molecular cloud cores, but the abundance of H 2 C 4 is significantly larger than predicted.}
}