The NKaKc = 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 NH<sub>2</sub> 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

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