@article{2041-8205-769-2-L19,
  author={S. Spezzano and S. Brünken and P. Schilke and P. Caselli and K. M. Menten and M. C. McCarthy and L. Bizzocchi and S. P.
Trevinõ-Morales and Y. Aikawa and S. Schlemmer},
  title={Interstellar Detection of c-C3D2},
  journal={The Astrophysical Journal Letters},
  volume={769},
  number={2},
  pages={L19},
  url={http://stacks.iop.org/2041-8205/769/i=2/a=L19},
  year={2013},
  abstract={We report the first interstellar detection of c-C 3 D 2 . Doubly deuterated cyclopropenylidene, a carbene, has been detected toward the starless cores TMC-1C and L1544 using the IRAM 30 m telescope. The ##IMG## [http://ej.iop.org/images/2041-8205/769/2/L19/apjl471523ieqn1.gif] {$J_{K_a,K_c} = 3_{0,3} \hbox{--} 2_{1,2}$} , 3 1, 3 -2 0, 2 , and 2 2, 1 -1 1, 0 transitions of this species have been observed at 3 mm in both sources. The expected 1:2 intensity ratio has been found in the 3 0, 3 -2 1, 2 and 3 1, 3 -2 0, 2 lines, belonging to the para and ortho species, respectively. We also observed lines of the main species, c-C 3 H 2 , singly deuterated c-C 3 HD, and the species with one 13 C off of the principal axis of the molecule, c-H 13 CC 2 H. The lines of c-C 3 D 2 have been observed with high signal-to-noise ratio, better than 7.5σ in TMC-1C and 9σ in L1544. The abundance of doubly deuterated cyclopropenylidene with respect to the normal species is found to be 0.4%-0.8% in TMC-1C and 1.2%-2.1% in L1544. The deuteration of this small hydrocarbon ring is analyzed with a comprehensive gas-grain model, the first including doubly deuterated species. The observed abundances of c-C 3 D 2 can be explained solely by gas-phase processes, supporting the idea that c-C 3 H 2 is a good indicator of gas-phase deuteration.}
}