A&A 464, L33-L36 (2007)
Laboratory detection of the negative molecular ion CCH-S. Brünken1, C. A. Gottlieb1, H. Gupta1, 2, M. C. McCarthy1, and P. Thaddeus1
1 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA, and Division of Engineering and Applied Sciences, Harvard University, 29 Oxford Street, Cambridge, MA 02138, USA
2 Institute for Theoretical Chemistry, Department of Chemistry and Biochemistry, The University of Texas, Austin, TX 78712, USA
(Received 19 December 2006 / Accepted 19 January 2007)
Aims.This paper reports the laboratory detection of the rotational spectrum of the acetylide anion, CCH-.
Methods.Five successive rotational transitions have been measured to high accuracy in a dc discharge with a free space millimeter-wave spectrometer in the frequency range 83-417 GHz.
Results.Precise spectroscopic constants have been obtained for CCH- and transition rest frequencies can now be calculated to better than 1 km s-1 in equivalent radial velocity far into the terahertz region, allowing for deep astronomical searches for this anion in space. The highly stable and fairly polar CCH- anion is a likely candidate for radio astronomical detection, its neutral analogue CCH being among one of the most abundant molecules in a wide variety of astrophysical sources.
Key words: line: identification -- molecular data -- astrochemistry -- methods: laboratory -- ISM: molecules -- radio lines: ISM
© ESO 2007