The millimeter- and submillimeter-wave spectrum of HC3N in the ground and vibrationally excited states

The pure rotational spectrum of the astrophysically very important linear m olecule cyanoacetylene, HC3N, in the ground and vibrationally excited stare s has been studied in selected regions from 118 to 814 GHz using the Cologn e terahertz spectrometer. Vibrational satellites appendant to the following vibrational states have been recorded and analyzed (v(4), v(5), v(6), v(7) ): (0, 0, 0, 1), (0, 0, 0, 2), (0, 0, 1, 0), (0, 0, 1, 1), (1, 0, 0, 0), (1 , 0, 0, 1), and the Fermi resonance systems (0, 1, 0, 0)/(0, 0, 0, 3) and ( 1, 0, 0, 2)/(0, 2, 0, 0)(0e). With the exception of the latter resonance sy stem, all states have been fitted within experimental accuracy. This work p rovides improved rest frequencies for the astronomical community and may al so be beneficial in the improvement of global fits. (C) 2000 Academic Press .