MICROWAVE-SPECTRUM OF SULFUR DIFLUORIDE IN THE 1ST EXCITED VIBRATIONAL-STATES VIBRATIONAL POTENTIAL FUNCTION AND EQUILIBRIUM STRUCTURE

Microwave spectra of SF2 in the first excited states of the three normal modes were observed and analyzed. A comparison of the observed inertia defects in the ν1 and ν3 states with those calculated by omitting the contributions of the Coriolis interaction between the two modes led to a ν ̃1 - ν ̃3 vibrational frequency differences of 25.72 ± 0.33 cm-1, with ν1 being definitely higher. The inertia defect in the ground state and our measured values for the inertia defect in the ν2 state and for the ν ̃1 - ν ̃3 difference were combined with the centrifugal distortion constants of Kirchhoff et al. [J. Mol. Spectrosc. 48, 157-164 (1973)] to improve the harmonic force field. The interaction constant between the two SF stretching coordinates was determined precisely. The third-order and the cubic anharmonic potential constants were calculated from the observed vibration-rotation constants. The equilibrium structure was determined to be re(SF) = 1.58745 ± 0.00012 A ̊ and θe(FSF) = 98.048 ± 0.013°. © 1979.