First far-infrared high-resolution analysis of the ν₂ band of sulphur dioxide ³²S¹⁶O¹⁸O and ³²S¹⁸O₂

F. Gueye , L. Manceron , A. Perrin (1, 2) , F. Kwabia Tchana , J. Demaison (3)

1 LISA (UMR_7583) - Laboratoire Interuniversitaire des Systèmes Atmosphériques
2 IPSL (FR_636) - Institut Pierre-Simon-Laplace
3 Université de Lille

High-resolution Fourier transform spectra of ¹⁸O-enriched isotopic samples of sulphur dioxide (³²S¹⁶O¹⁸O and ³²S¹⁸O₂) have been recorded at 0.00102 cm^-1 resolution in the 400-620 cm^-1 region at Synchrotron SOLEIL. These spectra have been recorded at low temperature 185 K using a 3.14 m optical path length cryogenic cell. This enables the first detailed infrared analysis of the ν₂ bands of the ³²S¹⁶O¹⁸O and ³²S¹⁸O₂ isotopologues of sulphur dioxide located at 507.36541(1) and 496.59988(1) cm^-1, respectively. Using a Watson-type Hamiltonian model to compute the upper and lower state energy levels, it was possible to reproduce the observed transitions. For both species, accurate rotational and centrifugal distortion constants were derived for the upper (0,1,0) vibrational state, while those of the (0,0,0) ground state were significantly updated. For this task, we combined the results of the present infrared measurements with the available literature microwave data in the (0,0,0) and (0,1,0) vibrational states. Finally, we took the opportunity of this study to compare the quality of the fit using an A- and S-type reduction for the Watson Hamiltonian.

Mots clés: Sulphur dioxide; far infrared; high-resolution spectra; line position analysis; Hamiltonian constants; iteratively reweighted least-squares method

Domaines: Planète et Univers [physics]

F. Gueye, L. Manceron, A. Perrin, F. Kwabia Tchana, J. Demaison. First far-infrared high-resolution analysis of the ν₂ band of sulphur dioxide ³²S¹⁶O¹⁸O and ³²S¹⁸O₂. Molecular Physics, 2016, 114, pp.2769-2776. ⟨10.1080/00268976.2016.1154619⟩. ⟨insu-03737477⟩