Rotational spectrum of formamide up to 1 THz and first ISM detection of its ν12 vibrational state⋆
1 Laboratoire de Physique des Lasers, Atomes, et Molécules, UMR CNRS 8523, Université de Lille 1, 59655 Villeneuve d’Ascq Cedex, France
2 Centro de Astrobiología (CSIC-INTA), Laboratory of Molecular Astrophysics, Department of Astrophysics, Ctra de Ajalvir, Km 4, 28850 Torrejón de Ardoz, Madrid, Spain
Received: 17 July 2012
Accepted: 21 September 2012
Context. Formamide is the simplest bearer of peptide bond detected in the interstellar medium (ISM).
Aims. There is still a lack of laboratory data on its rotational spectrum in the THz domain.
Methods. We measured the rotational spectrum of formamide in the frequency range 400–950 GHz. The ground and first excited vibrational state of the normal species as well as the ground state of 13C isotopic species were analysed.
Results. The results obtained represent an extension by a factor of two in frequency range compared to previous studies. Of all transition frequencies in the dataset about 45% are new measurements. A reliable set of rotational constants allows accurate predictions of transition frequencies in the THz domain. Based on the spectroscopic results, the ν12 = 1 excited vibrational state of formamide was detected in the IRAM 30 m line survey of Orion KL for the first time in the ISM.
Key words: line: identification / astronomical databases: miscellaneous / ISM: molecules / submillimeter: ISM / ISM: individual objects: Orion KL
Measured rotational transitions (Tables 4–6) are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (18.104.22.168) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/548/A71
© ESO, 2012