Millimeter- and submillimeter-wave spectra of the ONO′ bending mode (ν₇) in nitric acid

Over 140 rotational transitions have been assigned and measured for the ONO′ bending mode (ν₇) of gaseous nitric acid. These observations, over a wide range of J and K values in the region 100-600 GHz, have been used as the basis for an analysis of the rotational structure of this vibrational state. The resulting rotation-distortion parameters make possible the calculation, with good accuracy, of all the transition frequencies arising from thermally populated levels of the ν₇ vibrational state. Also, a novel spectrometer capable of broad spectral scans in the millimeter and submillimeter region is described.