One and two transitions of the A 3Π
X 3Σ electronic spectrum of imidogen
near 335 nm were detected in diffuse clouds toward
ζ Per and HD 27778, respectively:
D. M. Meyer and K. C. Roth,
Discovery of Interstellar NH
Astrophys. J. 376, L49L52 (1991).
The transitions involve an R(0) component in both cases as well as a Q(0) component of the v = 0 0 vibrational band system near 335.8 and 335.4 nm, respectively.
The detection of one fine struture component of the
N = 2 1 pure rotational transition
toward Sgr B2 was reported by
J. Cernicharo, J. R. Goicoechea, and E. Caux,
Far-Infrared Detection of C3 in Sagittarius B2 and IRC +10216
Astrophys. J. 534, L199L202 (2000);
a second fine structure component of that transition was 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, 214233 (2004).
A plethora of reports on observations of one or more fine structure
components of the N = 1 0 transition
in absorption carried out with Herschel/HIFI were reported
in the HIFI special issue of A&A. In, at least, most instances,
the observatioon of absorption lines indicates the presence of NH
in diffuse gas. The objects investigated include
a photon-dominated region: A. Fuente, O. Berné, J. Cernicharo, et al.:
Herschel Observations in the Ultracompact HII Region Mon R2 Water in Dense Photon-Dominated Regions (PDRs)
Astron. Astrophys. 521, Art. No. L23 (2010);
a young stellar object: A. O. Benz, S. Bruderer, E. F. van Dishoeck, et al.:
Hydrides in Young Stellar Objects: Radiation Tracers in a Protostar-Disk-Outflow System
Astron. Astrophys. 521, Art. No. L35 (2010);
the sight line toward a high-mass star-forminbg region: C. M. Persson, J. H. Black, J. Cernicharo, et al.:
Nitrogen Hydrides in Interstellar Gas Herschel/HIFI Observations towards G10.6-0.4 (W31C)
Astron. Astrophys. 521, Art. No. L45 (2010);
and another young stellar object: P. Hily-Blant, S. Maret, A. Bacmann, et al.:
Nitrogen Cydrides in the Cold Envelope of IRAS 16293-2422
Astron. Astrophys. 521, Art. No. L52 (2010).
In this context, also ND was observed in two fine structure components
of the N = 1 0 transition by:
A. Bacmann, E. Caux, P. Hily-Blant, et al.
First Detection of ND in the Solar-Mass Protostar IRAS 16293-2422
Astron. Astrophys. 521, Art. No. L42 (2010).