Terahertz spectroscopy of the 15NH2 amidogen radical

Context. The determination of isotopic ratios in interstellar molecules is a powerful probe of chemical routes leading to their formation. In particular, the ¹⁴N/¹⁵N abundance ratio of nitrogen-bearing species provides information on possible fractionation mechanisms. Up to now there is no accurate determination of this ratio in the interstellar medium (ISM) for the amidogen radical, NH₂.
Aims: This work is aimed at determining rotational frequencies of ¹⁵NH₂ to enable its astronomical detection, which will help to understand the formation mechanisms of nitrogen hydrides in the ISM.
Methods: We performed complementary measurements using both synchrotron-based, broadband far-infrared and high-resolution, submillimeter-wave frequencies to investigate the pure rotational spectrum of the ¹⁵NH₂ species.
Results: The first spectroscopic study of the ¹⁵N-isotopologue of the amidogen radical yielded an accurate set of molecular parameters.
Conclusions: Accurate frequencies are now available for ¹⁵NH₂ up to 7 THz (with N'' ≤ 13) allowing dedicated astronomical searches to be undertaken.

Full Table 2 (S1) and fitting files (S2-S4) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/591/A110