Knowledge Bank

The microwave spectrum of the SF radical in the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\pi 1/2$ state has been assigned in the frequency region from 40 to 180 GHz, utilizing the small Zeeman effect induced by spin-uncoupling with the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\pi 3/2$ state to distinguish lines due to SF from those due to other species. The spectrum was observed in glow discharge in mixtures of OCS and $CF4$. Previous $measurements1$ of the spectrum in the $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\pi 3/2$ state were extended to the 180 GHz region. Transition frequencies in both states were analyzed simultaneously and precise molecular constants including the rotational constant. $B0$, and the centrifugal distortion constant, $D0$, were obtained. The magnetic hyperfine coupling constants, a, b, c, and d of the fluorine nucleus interaction with the electron spin were all determined. An extremely small A-doubling constant was obtained, which suggests that close-lying $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma +$ and $\mathrm{<mrow\; data-mjx-texclass="ORD">2</mrow>}\Sigma -$ states are both contributing to the $\Lambda$-doubling.