¹³C¹⁶O₂: Global Treatment of Vibrational–Rotational Spectra and First Observation of the 2ν₁ + 5ν₃ and ν₁ + 2ν₂ + 5ν₃ Absorption Bands

Author： Tashkun S.A. Perevalov V.I. Lecoutre M. Huet T.R. Campargue A. Bailly D. Esplin M.P.

Publisher： Academic Press

ISSN： 0022-2852

Source： Journal of Molecular Spectroscopy, Vol.200, Iss.2, 2000-04, pp. : 162-176

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Abstract

The effective operator approach is applied to the calculation of both line positions and line intensities of the ¹³C¹⁶O₂ molecule. About 11 000 observed line positions of ¹³C¹⁶O₂ selected from the literature have been used to derive 84 parameters of a reduced effective Hamiltonian globally describing all known vibrational–rotational energy levels in the ground electronic state. The standard deviation of the fit is 0.0015 cm^-1. The eigenfunctions of this effective Hamiltonian have then been used in fittings of parameters of an effective dipole-moment operator to more than 600 observed line intensities of the cold and hot bands covering the ν₂ and 3ν₂ regions. The standard deviations of the fits are 3.2 and 12.0% for these regions, respectively. The quality of the fittings and the extrapolation properties of the fitted parameters are discussed. A comparison of calculated line parameters with those provided by the HITRAN database is given. Finally, the first observations of the 2ν₁ + 5ν₃ and ν₁ + 2ν₂ + 5ν₃ absorption bands by means of photoacoustic spectroscopy (PAS) is presented. The deviations of predicted line positions from observed ones is found to be less than 0.1 cm^-1, and most of them lie within the experimental accuracy (0.007 cm^-1) once the observed line positions are included in the global fit.