Infrared spectroscopy of the NO3 radical Original Research Article

The infrared spectrum of the NO3 radical is observed by high-resolution Fourier transform spectroscopy, infrared and near-infrared diode laser spectroscopy, and the vibrational assignments of the observed bands are discussed. The molecular constants of NO3 in the ground electronic 2A2′ state have been re-determined by using observed combination differences derived from the infrared spectrum between 1300 and 8000 cm−1, as follows, B=0.458 5485(63), DN=0.1113(12), DNK=−0.2121(27)×10−5, ϵbb=−0.016 49(13) cm−1, with one standard deviation in parentheses. The 1927 cm−1 band observed by a Fourier transform spectrometer has been newly analyzed, and molecular constants of the upper state are determined.