The electric and magnetic interactions which determine the hfs of the v=0, $J=1\mathrm{}$ 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 $\frac{\left(e{q}_1{Q}_1\right)}{h}=(-70.3405\mathrm{}\pm 0.0004)$ Mc/sec and $\frac{\left(e{q}_1{Q}_1\right)}{h}=-(34.0313\mathrm{}\pm 0.0010)$ Mc/sec, respectively. Hence the ratio of the Rb nuclear quadrupole moments is $\frac{Q_{85}}{Q_{87}}=+(2.06694\mathrm{}\pm 0.00006)$. 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 $c_1\left({\mathrm{I}}_1·\mathrm{J}\right)$ is $\frac{c_1}{h}=+(0.525\mathrm{}\pm 0.010)$ kc/sec, the constant of the spin-rotation interaction involving the F nucleus $c_2\left({\mathrm{I}}_2·\mathrm{J}\right)$ is $\frac{c_2}{h}=+(10.53\mathrm{}\pm 0.07)$ kc/sec, and the constant of the electron-coupled nuclear dipole-dipole scalar interaction $c_4\left({\mathrm{I}}_1·{\mathrm{I}}_2\right)$ is $\frac{c_4}{h}=+(0.23\mathrm{}\pm 0.06)$ kc/sec. In ${\mathrm{Rb}}^{87}$F, these interaction constants are $\frac{c_1}{h}=+(1.595\mathrm{}\pm 0.050)$ kc/sec, $\frac{c_2}{h}=+(10.51\mathrm{}\pm 0.08)$ kc/sec, and $\frac{c_4}{h}=+(0.66\mathrm{}\pm 0.10)$ kc/sec. The Hamiltonian also includes a nuclear dipole-dipole tensor term, and the interaction constants are $\frac{c_3}{h}=+(0.93\mathrm{}\pm 0.05)$ kc/sec and $\frac{c_3}{h}=+(3.16\mathrm{}\pm 0.18)$ kc/sec in ${\mathrm{Rb}}^{85}$F and ${\mathrm{Rb}}^{87}$F, respectively. These agree very well with values calculated from ($\frac{g_1{g}_2\mu N^2{〈R^{-3\mathrm{}}〉}_{\mathrm{av}}}{h}$), 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 $\frac{\left(e{q}_1{Q}_1\right)}{h}=-(7932.9\mathrm{}\pm 0.2)$ kc/sec and $\frac{\left(e{q}_1{Q}_1\right)}{h}=-(9656.9\mathrm{}\pm 0.6)$ kc/sec for ${\mathrm{K}}^{39}$F and ${\mathrm{K}}^{41}$F, respectively. The ratio of the $K$ nuclear quadrupole moments is $\frac{Q_{39}}{Q_{41}}=+(0.8215\mathrm{}\pm 0.0001)$. The observed ${\mathrm{K}}^{39}$F spectrum also allowed the determination of the interaction constants: $\frac{c_1}{h}=(270\mathrm{}\pm 20)$ cps; $\frac{c_2}{h}=(10.67\mathrm{}\pm 0.08)$ kc/sec; $\frac{c_3}{h}=(540\mathrm{}\pm 70)$ cps; $\frac{c_4}{h}=(30\mathrm{}\pm 80)$ 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.

• Received 31 October 1966

DOI:https://doi.org/10.1103/PhysRev.161.15