DETERMINATION OF THE MOLECULAR-CONSTANTS OF INTERACTING BRIGHT AND DARK STATES - ANALYSIS OF THE HIGH-RESOLUTION INFRARED-SPECTRUM OF THE S-O STRETCHING FUNDAMENTAL OF THIONYLIMIDE, HNSO

The S-O stretching fundamental, nu(2), of thionylimide has been record ed at high resolution and rotationally analyzed for the first lime. Th is strong A-type hand with origin al 1257.5808 cm(-1) is extensively p erturbed by the 5(1)6(1) state at 1206.58 cm(-1) through a- and b-axis Coriolis interactions. Even though no nu(5)+nu(6) band transitions co uld be Found. a complete analysis of the perturbed rotational structur e has been achieved. Accurate molecular constants for the ''bright'' 2 (1) state and the ''dark'' 5(1)6(1) state have been obtained, using a Hamiltonian that includes both types of Coriolis interactions. Further small perturbations at high k(a) and J have been identified as higher -order interactions with the nu(3) band at much lower energy. (C) 1996 American Institute of Physics.