Abstract
We report precise measurement of hyperfine intervals in the D1 lines of 7 Li. Laser spectroscopy is performed in a collimated atomic beam and the laser-induced fluorescence is detected. The laser frequency determination is achieved by measuring the beat frequency between the spectroscopy laser and a reference laser which is frequency-stabilized to a molecular iodine transition and is calibrated by an optical frequency comb. We obtain a value of 91.892(7) MHz for the splitting in the 2P1/2 state, and 803.509(16) MHz for that in the 2S1/2 state. Our result resolves a discrepancy between former measurements and is consistent with most theoretical predictions. © 2013 IOP Publishing Ltd.