Hyperfine Structure of the v=0, J=1 State in Rb 85 F, Rb 87 F, K 39 F, and K 41 F by the Molecular-Beam Electric-Resonance Method

The electric and magnetic interactions which determine the hfs of the v=0, $J=1$ state in ${\mathrm{Rb}}^{85}$F, ${\mathrm{Rb}}^{87}$F, ${\mathrm{K}}^{39}$F, and ${\mathrm{K}}^{41}$F have been obtained from spectra measured in zero magnetic field and near zero electric field. A molecular-beam electric-resonance apparatus with two-wire-type focusing fields and a single 30-cm transition field was used. For ${\mathrm{Rb}}^{85}$F and ${\mathrm{Rb}}^{87}$F the electric quadrupole interaction constants are $\frac{(e{q}_{1}{Q}_{1})}{h}=(\ensuremath{-}70.3405\ifmmode\pm\else\textpm\fi{}0.0004)$ Mc/sec and $\frac{(e{q}_{1}{Q}_{1})}{h}=\ensuremath{-}(34.0313\ifmmode\pm\else\textpm\fi{}0.0010)$ Mc/sec, respectively. Hence the ratio of the Rb nuclear quadrupole moments is $\frac{{Q}_{85}}{{Q}_{87}}=+(2.06694\ifmmode\pm\else\textpm\fi{}0.00006)$. Comparison with data on the electric quadrupole interaction constants for ${\mathrm{Rb}}^{85}$Cl and ${\mathrm{Rb}}^{87}$Cl gives no evidence of a contribution from nuclear electric polarization. In ${\mathrm{Rb}}^{85}$F, the constant of the spin-rotation interaction involving the Rb nucleus ${c}_{1}({\mathrm{I}}_{1}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{J})$ is $\frac{{c}_{1}}{h}=+(0.525\ifmmode\pm\else\textpm\fi{}0.010)$ kc/sec, the constant of the spin-rotation interaction involving the F nucleus ${c}_{2}({\mathrm{I}}_{2}\ifmmode\cdot\else\textperiodcentered\fi{}\mathrm{J})$ is $\frac{{c}_{2}}{h}=+(10.53\ifmmode\pm\else\textpm\fi{}0.07)$ kc/sec, and the constant of the electron-coupled nuclear dipole-dipole scalar interaction ${c}_{4}({\mathrm{I}}_{1}\ifmmode\cdot\else\textperiodcentered\fi{}{\mathrm{I}}_{2})$ is $\frac{{c}_{4}}{h}=+(0.23\ifmmode\pm\else\textpm\fi{}0.06)$ kc/sec. In ${\mathrm{Rb}}^{87}$F, these interaction constants are $\frac{{c}_{1}}{h}=+(1.595\ifmmode\pm\else\textpm\fi{}0.050)$ kc/sec, $\frac{{c}_{2}}{h}=+(10.51\ifmmode\pm\else\textpm\fi{}0.08)$ kc/sec, and $\frac{{c}_{4}}{h}=+(0.66\ifmmode\pm\else\textpm\fi{}0.10)$ kc/sec. The Hamiltonian also includes a nuclear dipole-dipole tensor term, and the interaction constants are $\frac{{c}_{3}}{h}=+(0.93\ifmmode\pm\else\textpm\fi{}0.05)$ kc/sec and $\frac{{c}_{3}}{h}=+(3.16\ifmmode\pm\else\textpm\fi{}0.18)$ kc/sec in ${\mathrm{Rb}}^{85}$F and ${\mathrm{Rb}}^{87}$F, respectively. These agree very well with values calculated from ($\frac{{g}_{1}{g}_{2}\ensuremath{\mu}{N}^{2}{〈{R}^{\ensuremath{-}3}〉}_{\mathrm{av}}}{h}$), so that there is no evidence for a tensor part of the electron-coupled nuclear dipole-dipole interaction in RbF. The electric quadrupole interaction constants are $\frac{(e{q}_{1}{Q}_{1})}{h}=\ensuremath{-}(7932.9\ifmmode\pm\else\textpm\fi{}0.2)$ kc/sec and $\frac{(e{q}_{1}{Q}_{1})}{h}=\ensuremath{-}(9656.9\ifmmode\pm\else\textpm\fi{}0.6)$ kc/sec for ${\mathrm{K}}^{39}$F and ${\mathrm{K}}^{41}$F, respectively. The ratio of the $K$ nuclear quadrupole moments is $\frac{{Q}_{39}}{{Q}_{41}}=+(0.8215\ifmmode\pm\else\textpm\fi{}0.0001)$. The observed ${\mathrm{K}}^{39}$F spectrum also allowed the determination of the interaction constants: $\frac{{c}_{1}}{h}=(270\ifmmode\pm\else\textpm\fi{}20)$ cps; $\frac{{c}_{2}}{h}=(10.67\ifmmode\pm\else\textpm\fi{}0.08)$ kc/sec; $\frac{{c}_{3}}{h}=(540\ifmmode\pm\else\textpm\fi{}70)$ cps; $\frac{{c}_{4}}{h}=(30\ifmmode\pm\else\textpm\fi{}80)$ cps. We point out that experimental evidence for nuclear polarizability of Br nuclei is provided by data of others on the electric quadrupole interaction constants of ${\mathrm{Br}}^{79}$ and ${\mathrm{Br}}^{81}$ in the Br atom and in LiBr.