New High-Resolution Analysis of the 3ν3 and 2ν1 + ν3 Bands of Nitrogen Dioxide (NO2) by Fourier Transform Spectroscopy

Abstract

Using new high-resolution Fourier transform spectra recorded at the University of Denver in the 2-μm region, a new and more extended analysis of the 2ν1 + ν3 and 3ν3 bands of nitrogen dioxide, located at 4179.9374 and 4754.2039 cm−1, respectively, has been performed. The spin–rotation energy levels were satisfactorily reproduced using a theoretical model that takes into account both the Coriolis interactions between the spin–rotation energy levels of the (201) vibrational “bright” state with those of the (220) “dark” state. The interactions between the (003) bright state with the (022) dark state were similarly treated. The spin–rotation resonances within each of the NO2 vibrational states were also taken into account. The precise vibrational energies and the rotational, spin–rotational, and coupling constants were obtained for the two dyads {(220), (201)} and {(022), (003)} of the 14N16O2 interacting states. From the experimental line intensities of the 2ν1 + ν3 and 3ν3 bands, a determination of their vibrational transition moment constants was performed. A comprehensive list of line positions and line intensities of the {2ν1 + 2ν2, 2ν1 + ν3} and the {2ν2 + 2ν3, 3ν3} interacting bands of 14N16O2 was generated. In addition, assuming the harmonic approximation and using the Hamiltonian constants derived in this work and in previous studies (A. Perrin, J.-M. Flaud, A. Goldman, C. Camy-Peyret, W. J. Lafferty, Ph. Arcas, and C. P. Rinsland, J. Quant. Spectrosc. Radiat. Transfer 60, 839–850 (1998)), we have generated synthetic spectra for the {(022), (003)}–{(040), (021), (002)} hot bands at 6.3 μm and for the {(220), (201)}–{(100), (020), (001)} hot bands at 3.5 μm, which are in good agreement with the observed spectra.