DETERMINATION OF THE MOLECULAR-CONSTANTS FOR INTERACTING BRIGHT AND DARK STATES - ANALYSIS OF THE HIGH-RESOLUTION INFRARED-SPECTRUM OF THE NU(8) BAND OF SULFINE, H2CSO

Gas-phase infrared spectra of the transient molecule sulfine, H2CSO, h ave been recorded in pyrolysis experiments using methanesulfinyl chlor ide or dimethyl sulfoxide as starting materials. Two strong vibrationa l fundamentals, upsilon(4) (a', 1175 cm(-1)) and upsilon(8) (a '' 762 cm(-1)), have been observed at low resolution in the 1400-700 cm(-1) r egion. The upsilon(8) band has been recorded at high resolution and a detailed analysis of the rotational structure has been carried out. Nu merous excited state perturbations result from \Delta K-a\ = 2 A-type and \Delta K-a\ = 1 B-type Coriolis interactions with the 7(2) vibrati onal state at 784.2 cm(-1). Although 2 upsilon(7) band transitions cou ld not be directly observed, a complete analysis of the perturbed rota tional, structure has been possible, using a Hamiltonian which include s both types of Coriolis interactions. Accurate molecular constants ha ve been obtained for both states with only two interaction constants, one for each mechanism. A few weak perturbations at very high K-a valu es could not be fitted with this scheme and are assigned to high order Coriolis interactions with the 6(1) level at 866 cm(-1). (C) 1995 Aca demic Press, Inc.