Spin-Rotation Coupling in the Alkali—Rare-Gas Van der Waals Molecule KAr

We report results of a molecular-beam magnetic-resonance study of the paramagnetic Van der Waals molecule KAr. The experiment yields a value for the spin-rotation interaction $\hslash \gamma \overrightarrow{\mathrm{S}}·\overrightarrow{\mathrm{N}}$, where $\hslash \overrightarrow{\mathrm{S}}$ and $\hslash \overrightarrow{\mathrm{N}}$ are, respectively, the electronic and rotational angular momentum. The average spin-rotation constant in KAr is $\overline{\gamma }=0.24\mathrm{}\left(1\right)\mathrm{}$ MHz.