The v₃ and v₄ interacting bands of HNO₃ line positions and line intensities

Abstract

Very high resolution Fourier transform spectra of HNO₃ recorded in the 1230–1370 cm^-1 spectral region have been extensively analysed leading to precise line positions and intensities for the v ₃ and v ₄ bands of this molecule. Then, using a hamiltonian which takes explicitly into account the Fermi and Coriolis resonances between these two bands, it has been possible to reproduce satisfactorily the majority of the v ₃ and v ₄ interacting rotational levels. Moreover resonances due to unobserved vibrorotational levels are discussed. Intensities of 218 individual transitions belonging to the v ₃ and v ₄ bands were measured allowing a precise determination of the constants involved in the expansion of the corresponding transition moment operators. Finally a complete synthetic spectrum of the v ₃ and v ₄ bands of HNO₃ has been computed.