Measurement of the hyperfine structure splitting for the 4 and 52 P 1/2 states of sodium using radio-frequency spectroscopy

The hyperfine-structure splitting for the 4 and 5² P ^1/2 states of sodium was measured using step-wise laser excitation combined with rf-resonance techniques. The magnetic dipole interaction constants were found to be a(4² P _1/2)=30.4(5) MHz and a(5₂ P _1/2) =13.3(2) MHz. The results are compared with a theoretical calculation, taking polarization effects into account.