Astronomical identification of CN^-, the smallest observed molecular anion

  title={Astronomical identification of CN^-, the smallest observed molecular anion},
  author={Marcelino Ag{\'u}ndez and Jos{\'e} Cernicharo and M. Gu{\'e}lin and Claudine Kahane and {\`E}velyne Roueff and Jacek Kłos and F. Javier Aoiz and F. Lique and N. Marcelino and Javier R. Goicoechea and M. Gonzalez Garcia and Carl A. Gottlieb and Michael C. McCarthy and Patrick Thaddeus},
We present the first astronomical detection of a diatomic negative ion, the cyanide anion CN-, as well as quantum mechanical calculations of the excitation of this anion through collisions with para-H2. CN- is identified through the observation of the J = 2-1 and J = 3-2 rotational transitions in the C-star envelope IRC +10216 with the IRAM 30-m telescope. The U-shaped line profiles indicate that CN-, like the large anion C6H-, is formed in the outer regions of the envelope. Chemical and… 

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