Measurement of the fine-structure splitting of the 42 D state of lithium using level-crossing spectroscopy

The fine-structure splitting of the 4² D state in lithium was measured using stepwise laser excitation combined with level-crossing spectroscopy. The splitting was determined to be 456.2(0.8) MHz, a considerably higher value than the one obtained in a recent level-anticrossing measurement. The new value is in good agreement with the result of a Hartree-Fock calculation, 460.2 MHz.