THE H2SH_{2}S SPECTRUM BETWEEN 2150 AND 2950cm−12950 cm^{-1} : LINE POSITIONS AND INTENSITIES

Author Institution: Laboratoire de Physique Mol\'{e}culaire et d'Optique Atmosph\'{e}rique, C.N.R.S, B\v{a}timent 221; Herzberg Institute of Astrophysics, N.R.C, OttawaSpectra of natural hydrogen sulfide have been recorded between 2150 and $2950 cm^{-1}$ on a Bomem spectrophotometer with a resolution of $0.010 cm^{-1}$. The careful analysis of the $2\nu_{2}, \nu_{1}$ and $\nu_{3}$ bands of the three species $H_{2}^{32}S,H_{2}^{33}S$ and $H_{2}^{34}S$ has led to a complete and precise set of rotational energy levels of the three vibrational interacting states (020), (100) and (001) for the three isotopes. Then using these data we have been able to determine the rotational and coupling constants involved in the upper-states Hamiltonian. About 530 line intensities of $H_{2}^{32}S$ were measured from which precise transition moments of the 3 bands under study were derived leading to the determination of the first derivatives of the dipole moment with respect to the normal coordinates $q_{1}$ and $q_{3}$. Besides it is to be pointed out that the strong intensity anomalies appearing in the $\nu_{3}$ band are well reproduced by the calculation. Finally the complete spectrum of natural hydrogen sulfide has been computed

The far infrared spectrum of H2O2 observed and calculated rotational levels of the torsional states : (n, τ) = (0, 1), (0, 3) and (1, 1)

High resolution Fourier transform spectra, recorded between 30 and 460 cm-1, have been used for an extensive analysis of the (n, τ) = (0, 3) ← (n', τ') = (0, 1), (0,1) ← (0, 3) and (1, 1) ← (0, 3) torsion-rotation bands of H2O2. Then, using a Hamiltonian which takes explicitly into account the strong |ΔKa| = 2 interaction between the rotational levels of the (n, τ) = (0,1) and (1,1) torsional states, as well as the |ΔKa| = 2 interaction between the (n, τ) = (1, 1) and (2, 1) rotational levels, it has been possible to reproduce very satisfactorily the experimental rotational levels of the (n, τ) = (0, 1) and (1,1) torsional states and a precise set of torsional energies and rotational and coupling constants has been derived. In the same way, to fit the (n, τ) = (0, 3) experimental energy levels we have used a Hamiltonian taking into account the |ΔKa| = 2 interaction between the rotational levels of the (n, τ) = (0, 3) and (1, 3) torsional states, and this calculation has also provided a precise set of torsional energies, rotational and coupling constants for the (n, τ) = (0, 3) and (1, 3) torsional states.Des spectres par transformée de Fourier à haute résolution enregistrés entre 30 et 460 cm-1 ont été utilisés pour une analyse systématique des bandes de torsion-rotation (n, τ) = (0, 3) ← (n', τ') = (0,1), (0,1) ← (0, 3) et (1, 1) ← (0, 3) de H2O 2. L'utilisation d'un hamiltonien qui traite explicitement la forte interaction de type |ΔKa| = 2 entre les niveaux rotationnels des états de torsion (n, τ) = (0, 1) et (1,1) ainsi que l'interaction en |ΔKa| = 2 entre les niveaux de (n, τ) = (1,1) et (2, 1), a permis de reproduire de façon très satisfaisante les niveaux observés des états de torsion (n, τ) = (0,1) et (1,1) tout en foumissant un ensemble précis d'énergies de torsion et de constantes rotationnelles et de couplage. De la même façon pour reproduire les niveaux observés de (n, τ)= (0, 3) a été utilisé un hamiltonien qui tient compte de l'interaction en |ΔK a| = 2 entre les niveaux rotationnels des états de torsion (n, τ) = (0, 3) et (1, 3) et des énergies de torsion et des constantes rotationnelles et de couplage précises ont été ainsi déterminées pour ces états