Hyperfine Structure in the Visible Molecular-Iodine Absorption Spectrum

The observed hyperfine structure in the visible iodine absorption spectrum can be explained as a combination of a nuclear electric quadrupole interaction in both the ground and excited electronic states with a difference in coupling constants $(eQ{q}^{\prime }-eQ{q}^{\prime \prime })=-958\mathrm{}\pm 15$ MHz (0.032 ${\mathrm{cm}}^{-1\mathrm{}}$) and a magnetic hyperfine interaction in the excited state with a coupling constant of 500±100 MHz (0.017 ${\mathrm{cm}}^{-1\mathrm{}}$).