Off-Diagonal Hyperfine Structure inSc45

The three independent coefficients in the magnetic-dipole hyperfine Hamiltonian cannot be determined by measurements of the hfs constants of the two atomic states $3d4s^2{}_{}{}^2{}_{}{}^{}D_{\frac{3}{2},\frac{5}{2}}^{}{}_{}{}^{}$. However, the interaction between these states at a high magnetic field shifts the resonance frequencies for transitions between magnetic substates of either state, and the necessary additional information for evaluating the coefficients may be obtained by observing these frequency shifts. Such measurements, together with more accurate low-field determinations of the hfs constants, lead to ratios of the coefficients in the dipole hfs Hamiltonian in agreement with a recent theoretical prediction. More precise values for the electron $g$ factors are also reported.