New line positions analysis of the ν1+ν2+ν3 band of NO2 at 3637.848 cm−1

Abstract

Using high resolution Fourier transform spectra, a new investigation of the ν1+ν2+ν3 absorption band of nitrogen dioxide, 14N16O2, located at 3637.8479(3)cm−1 was performed. The assigned ν1+ν2+ν3 lines involve energy levels of the (1,1,1) vibrational state with rotational quantum numbers up to Ka=12 and N=54. The energy levels were satisfactorily reproduced within their experimental uncertainty using a theoretical model which takes explicitly into account the Coriolis interactions coupling the (1,1,1) levels with those of the (1,3,0) and (2,1,0) dark states, together with the spin–rotation interactions within (1,1,1) and (1,3,0) and (2,1,0). As a consequence, precise vibrational energies, rotational, spin–rotational and coupling constants were achieved for the triad {(2,1,0),(1,3,0),(1,1,1)} of interacting states of 14N16O2. Using these parameters together with the transition moment operator of the ν1+ν3 band achieved during previous studies [Mandin JY, Dana V, Perrin A, Flaud JM, Camy-Peyret C, Régalia L, Barbe A, J Mol Spectrosc 1997;181: 379–388], we have generated an improved set of line parameters (line positions and line intensities) for the ν1+ν2+ν3−ν2 hot band of 14N16O2 which absorbs together with the ν1+ν3 cold band in the 3.4µm region.