In summary, extended and more precise frequency measurements performed with the Cologne terahertz spectrometer have led to an improved set of molecular constants for the NH radical in its vibrational ground state. An additional hyperfine coupling constant, , could be determined for the 14 N nucleus in NH for the first time.
The frequencies reported in this work may be useful for an interstellar detection of the rotational transition, though a ground-based observation will be difficult because of the reduced atmospheric transmission in the terahertz region. However, this frequency range is accessible to airborne or spaceborne observatories. For ground-based observations, the newly observed transitions at 946 GHz, located 41 GHz lower than the atmospheric water line, are most suitable for further interstellar investigations on NH.
© European Southern Observatory (ESO) 1997
Online publication: June 5, 1998