Direct observation of hyperfine splittings of theLi72P3/2state by subnatural linewidth spectroscopy

Abstract

The hyperfine splittings of ${}_{}{}^7{}_{}{}^{}\mathrm{Li}$ 2$P_{3/2}$→2$S_{1/2}$, which are normally masked within the natural linewidth, are directly resolved for the first time by a line-narrowing technique of laser-induced fluorescence spectroscopy with use of a phase-switched laser. Observed splittings of 2$P_{3/2}$ levels are 9.41±0.10 MHz for (F’=2)-(F’=3), 6.00±0.16 MHz for 1-2, and 2.88±0.30 MHz for 0-1, which are consistent with reported hyperfine constants.