Fine and hyperfine structure of the 3P2 term in lithium

The fine and hyperfine structures of the 3p2 term in Li7 have been studied by the technique of level-crossing spectroscopy. A preliminary value for the fine-structure separation is Δν=2882.9±1.2 Mc/sec. It is expected that the present technique can be extended to obtain a result that is reliable to a few parts per million. It is noteworthy that the fine-structure intervals in lithium are 8% and 12% smaller for the 2p and 3p levels, respectively, than the corresponding intervals in hydrogen. A theory is developed for interpreting the separation between hyperfine level crossings. Its application depends on a detailed knowledge of the core-polarization effects of the 3p electron. Evidence is presented indicating that the core-polarization effects in the np states n=2,3 scale as 1r3np for the valence electron. Assuming this to be true, we estimate that ae(3p)=-3.05(12) Mc/sec for Li7. The limited precision achieved so far in this work has prevented observation of the Li7 quadrupole interaction.