High-precision laser-rf double-resonance spectroscopy of theΣ2ground state of CaF

Abstract

The laser-rf double-resonance technique has been applied to achieve high-precision measurements of the $N$ dependence of the spin-rotation and hyperfine interaction in the ${}_{}{}^2{}_{}{}^{}\Sigma (v^{\prime \prime }=0)$ ground state of CaF in a molecular beam. The effective spin-rotation-interaction constant is shown at small $N$ to depart markedly from the asymptotic value found at large $N$, and the average hfs splitting of the $J^{\prime \prime }=N+\frac{1}{2}$ and $J^{\prime \prime }=N-\frac{1}{2}$ levels is shown to exhibit a maximum for $N=11-12\mathrm{}$. These newly observed effects, though consistent with the theory, have not been explicitly predicted previously.