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Line intensity measurements in 14N2 16O and their treatment using the effective dipole moment approach: I. The 4300- to 5200-cm-1 Region

par Daumont, Ludovic;Vander Auwera, Jean ;Teffo, Jean Luc;Perevalov, Valery;Tashkun, Sergeï
Référence Journal of Molecular Spectroscopy, 208, 2, page (281-291)
Publication Publié, 2001

Article révisé par les pairs

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Résumé :

This work continues a series of publications devoted to the application of the effective operator approach to the vibrational-rotational treatment of linear triatomic molecules, aiming at the analysis and prediction of their infrared spectra. In that frame work, we have started a large-scale work aiming at the global description of line intensities of cold and hot bands of 14N2 16O in its ground electronic state in the spectral range above 3600 cm-1. In 14N2 16O, vibrational interacting levels group in polyads as a result of the relation 2ω1 ≈ 4ω2 ≈ ω3 existing between the harmonic frequencies. The polyads are identified by the so-called polyad number P = 2V1 + V2 + 4V3. The work described in the present paper concerns bands associated with transitions corresponding to ΔP = 7, 8, and 9. The absorption spectra of N2O at room temperature have been recorded at a resolution of 0.007 cm-1 in the range from 4300 to 5200 cm-1 using a Bruker IFS120HR Fourier transform spectrometer. Sample pressure/absorption path length products ranging from 7 to 1753 mbar x m have been used. More than 3000 absolute line intensities have been measured in 66 different bands belonging to the ΔP = 7, 8, and 9 series. Dicke narrowing has been observed in the high-pressure spectra. Using wavefunctions previously determined from a global fit of an effective Hamiltonian to about 18,000 line positions (S. A. Tashkun, V. I. Perevalov, and J.-L. Teffo to be published), the experimental intensities measured in this work and by R. A. Toth (J. Mol. Spectrosc. 197, 158-187 (1999)) were fitted to 47 parameters of a corresponding effective dipole moment, with residuals very close to the experimental uncertainty. Examples are given showing that the modeling reproduces intensities of perturbed lines well. © 2001 Academic Press.