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Abstract
The vibrational term values, principal rotational constants and centrifugal distortion constants of the 1 B 2 state of SO2 at 42 573 cm-1 (2350 Å)Footnote‡
1 Å = 10-10 m. 1 d = 1 dyne = 10-5 N. 1 u = 1 unified atomic mass unit ≈ 1·660 531 × 10-27 kg.
are interpreted in a unified treatment using (i) a vibrational hamiltonian based on a double minimum potential in the antisymmetrical stretching coordinate q 3 and strong anharmonic coupling of q 3 with the symmetric stretch q 1; and (ii) a modified treatment of Coriolis coupling and centrifugal distortion, in order to take account of the irregular intervals in the vibrational manifold. This treatment successfully explains a group of observed quantities, including isotopic data, relative intensities and inertial defects, which were not used in determining the constants of the potential function. The analysis indicates that there is a double minimum potential in the antisymmetric mode with a barrier of about 141 cm-1 at the C 2v configuration; the top of the barrier is probably significantly higher, by 43±20 cm-1, than the zero-point vibrational level, corresponding to an asymmetrical structure in this electronic state. Calculated equilibrium values of the short and long distances are respectively 1·491 and 1·639 Å.Contribution No. 195 from the Photochemistry Unit, University of Western Ontario.
Contribution No. 195 from the Photochemistry Unit, University of Western Ontario.
Notes
1 Å = 10-10 m. 1 d = 1 dyne = 10-5 N. 1 u = 1 unified atomic mass unit ≈ 1·660 531 × 10-27 kg.
Contribution No. 195 from the Photochemistry Unit, University of Western Ontario.