Observation of Zeeman Quantum Beats in Molecular Iodine

Zeeman quantum beats have been observed in the fluorescent emission from individual rotational levels of the $B{}_{}{}^3{}_{}{}^{}\Pi _{0\mathrm{u}}^{}{}_{}{}^{+}$ state of ${}_{}{}^{127}{}_{}{}^{}\mathrm{I}_2^{}{}_{}{}^{}$ after excitation by a short resonant dye-laser pulse. The derived Landé factors $g_J$ and $g_1$ (chemical shift) are compared with the spinrotation hyperfine coupling constants.