@article{1538-4357-547-1-L65,
  author={A. J. Apponi and M. E. Sanz and C. A. Gottlieb and M. C. McCarthy and P. Thaddeus},
  title={The Cyclic C5H Radical},
  journal={The Astrophysical Journal Letters},
  volume={547},
  number={1},
  pages={L65},
  url={http://stacks.iop.org/1538-4357/547/i=1/a=L65},
  year={2001},
  abstract={Cyclic C 5 H, the free radical formed by substituting an ethynyl group CCH for the hydrogen atom in the astronomical molecule c -C 3 H, has been detected in the laboratory in a supersonic molecular beam by Fourier transform microwave spectroscopy. Enough lines in the rotational spectrum have been measured to allow a deep search for this radical with radio telescopes. Contrary to theoretical prediction, c -C 5 H is apparently unsymmetrical, plausibly the result of pseudo-Jahn-Teller deformation.}
}