2012A&A...548A..71M

Formamide is the simplest bearer of peptide bond detected in the interstellar medium (ISM). There is still a lack of laboratory data on its rotational spectrum in the THz domain. We measured the rotational spectrum of formamide in the frequency range 400-950GHz. The ground and first excited vibrational state of the normal species as well as the ground state of ¹³C isotopic species were analysed. 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 30m line survey of Orion KL for the first time in the ISM.