High-J rotational transitions of NNO measured with the NAIR terahertz spectrometer

A BWO-based terahertz spectrometer has been constructed and tested by measuring some high-J rotational transitions of NNO in the frequency region from 620 to 730 GHz. The observed line center frequencies confirm the previously reported ones obtained by FTIR spectroscopy. The high sensitivity of the present spectrometer allowed us to record spectra of singly substituted isotopomers, (NNO)-N-15, (NNO)-N-15, (NNO)-O-18, and (NNO)-O-17, in natural abundance. The rotational and centrifugal distortion constants have been revised. (C) 1997 Academic Press.