FIRST ANALYSIS OF THE $3\nu_{g}- \nu_{g}, 3\nu_{g}- \nu_{5}$ AND $3\nu_{9} -2\nu_{5}$ BANDS OF $HNO_{3}$: TORSIONAL SPLITTING IN THE $\nu_{9}$ VIBRATIONAL MODE.

Author Institution: Laboratoire de Physique Mol\'{e}culaire et Applications, CNRS, Universit\'e Pierre et Marie Curie; Physikalish-Chemisches Institut, Justus-Liebig-Universitat; Department of Physics, University of Denver; Atmospheric Sciences Division, NASA Langley Research CenterUsing Fourier transform spectra recorded at Giessen University and at Denver University in the 25$m\mu m$ and 12$\mu m$ spectral regions respectively, it has been possible to perform the first analysis of the $3 \nu_{5} \nu_{5}$ and $3 \nu_{9} - \nu_{9}$ hot bands of $HNO_{3}$ located at $392.4 cm^{-1}$, $409.8 cm^{-1}$ and $830.4 cm^{-1}$ respectively. An accurate description of the torsional splitting in the $\nu_{9}=3$ vibrational state was achieved, leading to the determination of the two torsional band centers $E_{\nu_{9}=3.1}-1288.8451 cm^{-1}$ and $E_{\nu_{9}-3,2}=1288.9036 cm^{-1}$ and to the first determination of the $\nu_{9}$ torsional potential of $HNO_{3}$