High resolution molecular spectroscopy of the sulfur-containing XY2 type molecules.

In this thesis, we analyzed the high resolution absorption molecular spectra of H2S, D2S, HDS and SO2 registered for the first time or with better experimental characteristics as compared with those registered before. For the first time in the practice of rotation-vibrational spectroscopy in the frame of the devel- oped method of "global ftting" the analysis of 22 bands (as a whole more than 9700 rotation- vibrational lines) of D2S molecule is realized. This method of "global fitting" is developed with regard to molecules of Cs symmetry; on this basis a simultaneous analysis of all the known up to the present rotation-vibrational spectra of HDS molecule is realized. The SPGF method is applied to the three-atom molecules H2S, D2S, HDS. An original procedure of the identification of very weak lines is developed for the first time and practically realized for the example of "hot" lines of SO2 molecule. U(p+1) formalism is adapted to the three-atom non-linear molecules of C2v symmetry and the parameters of a vibrational Hamiltonian is developed in the case of the D2S molecule.Dans cette these, nous avons effectue l'analyse des spectres d'absorption a haute resolution de H2S, D2S, HDS et SO2 enregistres pour la premiere fois ou avec une meilleure precision experimentale que les spectres anterieurs. Nous avons developpe une methode originale de "global ftting" qui nous a permis l'analyse de 22 bandes vibrationnelles soit un total de 9700 transitions rovibrationnelles pour la molecule de D2S. Nous avons applique cette meme methode a des molecules de symmetrie Cs, en particulier tout le spectre rovibrationnel de la molecule HDS a ete analyse. La methode SPGF est appliquee aux molecules triatomiques H2S, D2S, HDS. Une procedure originale permettant l'identication des bandes tres peu intenses a ete mise au point pour la premiere fois et appliquee aux bandes chaudes de la molecule SO2. Le formalisme U(p+1) est adapte aux molecules triatomiques non lineaires de symmetrie C2v et les parametres d'un Hamiltonien vibrationnel sont determines dans le cas de la molecule D2S