The N_KaKc = 1₁₀ – 1₀₁ para rotational transition of amidogen, NH₂, was observed in absorption toward Sgr B2 (N) and (M):
E. F. van Dishoek, D. J. Jansen, P. Schilke, and T. G. Philips,
Discovery of the Interstellar NH₂ Radical
Astrophys. J. 416, L83–L86 (1993).
Three fine structure components were observed with partially resolved ¹⁴N hyperfine structure which obviously secures the identification.

Further transitions were reported in
J. R. Goicoechea, N. J. Rodríguez-Fernández and J. Cernicharo,
The Far-Infrared Spectrum of the Sagittarius B2 Region: Extended Molecular Absorption, Photodissociation, and Photoionization
Astrophys. J. 600, 214–233 (2004).

M. Melosso, L. Bizzocchi, O. Sipilä, B. M. Giuliano, L. Dore, F. Tamassia, M.-A. Martin-Drumel, O. Pirali, E. Redaelli, and P. Caselli
reported on the
First detection of NHD and ND2 in the interstellar medium — Amidogen deuteration in IRAS 16293–2422
Astron. Astrophys. 641, Art. No. A153 (2020).
Both isotopologs were detected in archival HIFI/Herschel data taken toward the Class 0 protostar IRAS 16293−2422. Very high degrees of deuteration were inferred.

A similar account was given shortly thereafter by
A. Bacmann, A. Faure, P. Hily-Blant, K. Kobayashi, H. Ozeki, S. Yamamoto, L. Pagani, and F. Lique,
Deuterium fractionation of nitrogen hydrides: detections of NHD and ND2
Mon. Not. R. Astron. Soc. 499, 1795 (2020).
NHD observations are based on archival APEX data, ND₂ observations on archival HIFI/Herschel data as above. The numbers are very similar to the ones above. One can deduce deuteration degrees per A atom of ~0.25 and ~0.35 for NHD and ND₂, respectively, from their total column densities.

Contributor(s): H. S. P. Müller; 03, 2007; 02, 2023