Microwave Spectrum of the SO Radical. Equilibrium S-O Distance, Electric Quadrupole Coupling Constant and Magnetic Hyperfine Structure Constants

The molecular constants in the first excited vibrational state of the ³² SO radical are obtained as well as in the ground state. The equilibrium constants are much improved; B _e =21609.5 ₅ ±0.15Mc/sec, λ _e =157780±25 Mc/sec, and r _e =1.48108±0.00005Å. Spectra of other two isotopic species, ³⁴ SO and ³³ SO, are also analyzed. Hyperfine interaction due to the ³³ S nucleus is studied in detail, and \({\langle}\sum\limits_{i}(3\cos^{2}\chi_{i}-1)/{2r_{i}}^{3}{\rangle}{=}-3.4{\times}10^{24}\)cm ^-3 , \({\langle}\sum\limits_{i}\{(3\cos^{2}\chi_{i}-1)/{2r_{i}}^{3}\}{\cdot}s_{iz}{\rangle}_{S_{z}{=}1}{=}-5.32{\times}10^{24}\)cm ^-3 , \({\langle}\sum\limits_{i}\delta(\textbf{\itshape r}_{i})s_{iz}{\rangle}_{S_{z}{=}1}{=}3.96{\times}10^{23}\)cm ^-3 are obtained. The Stark effect of the ³³ SO spectra is worked out in detail and utilized for the assignment of the weak lines.