@article{1538-4357-523-1-L89,
  author={C. D. Ball and M. C. McCarthy and P. Thaddeus},
  title={Laser Spectroscopy of the Carbon Chains HC7H and HC9H},
  journal={The Astrophysical Journal Letters},
  volume={523},
  number={1},
  pages={L89},
  url={http://stacks.iop.org/1538-4357/523/i=1/a=L89},
  year={1999},
  abstract={Strong vibronic bands of the 3 Σ ##IMG## [http://ej.iop.org/images/1538-4357/523/1/L89/img1.gif] {img1.gif} ← X 3 Σ ##IMG## [http://ej.iop.org/images/1538-4357/523/1/L89/img2.gif] {img2.gif} transition of the linear triplet radicals HC 7 H and HC 9 H have been measured in the gas phase by cavity ringdown spectroscopy. The origin band of HC 7 H and the origin and ν 3 bands of HC 9 H all exhibit well resolved P and R branches. For HC 9 H, the origin band is within 1 Å of the diffuse interstellar band λ5818, yet insufficiently close for positive identification. In both molecules, internal conversion is much more rapid than radiative emission, and fluorescence is not observed. Lower limits on the radiationless lifetime of the upper state of the origin band are determined to be 0.1 ns for HC 7 H and 0.01 ns for HC 9 H. Because the origin bands of these two radicals are about equally intense, it should be possible to detect longer members of the series in the gas phase.}
}