Hyperfine structure in ground multiplets of 17O and 19F

The hyperfine structure coupling constants of the ground 3P multiplet of 17O have been measured in a paramagnetic resonance experiment with a sample of enriched oxygen gas. They are: a2 = – 218.569 ± 0.004 Mc/s, a1 = 4.738 ± 0.036 Mc/s, a2,1 = –126.6 ± 2.0 Mc/s, a1,0 = – 91.7 ± 7.2 Mc/s, b2 = –10.438 ± 0.030 Mc/s, b1 = 5.199 ± 0.090 Mc/s. These results confirm the values of a2 and b2 reported previously by Kamper, Lea & Lustig 1957. Measurements have also been made on the excited level of the ground 2P multiplet of 19F. They yield: a½ = 10244.21 ± 0.03 Mc/s, gJ (J = ½) = 0.66561 ± 0.00003. An analysis of the magnetic hyperfine constants in the ground multiplets of 17O and 19F shows that in neither case do they yield consistent values for the two parameters <r-3> and |ψ(0)|2 usually associated with magnetic hyperfine structure. All measurements of hyperfine structure in these multiplets are consistent, however, with the requirements of LS coupling theory which introduce a third parameter into the magnetic hyperfine operator. The discrepancy is attributed to polarization effects, other than spin polarization of the core s electrons, brought about by the exchange interaction between electrons.