Electric dipole moment of SO2 in ground and excited vibrational states

Radiofrequency electric resonance spectra of SO2 molecular beams have been observed for a number of rotational levels of the (000), (100), (010), (001), (200), (110), (200), and (011) vibrational states. Heated supersonic nozzle beams of SO2 in argon were found to give enhanced signal-to-noise ratios. Stark effect measurements for the vibrational ground state give μ000=1.63305(4) D and polarizability anisotropies of αaa−αbb=1.62(40) Å3 and αaa−αcc=0.1(7) Å3. The dipole moment data for excited vibrational states can be expressed as μ=1.62673+0.00017(v1+1/2) − 0.00684(v2+1/2) + 0.01943(v3+1/2) − 0.00002(v1+1/2)2 + 0.00002(v1+1/2) (v2+1/2) − 0.00003(v2+1/2)2 − 0.00012(v2+1/2) (v3+1/2). By combining the Stark effect data with infrared intensity measurements, the electric dipole moment function for SO2 through second derivative terms has been determined.