摘要：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.
