Superhyperfine structure of theH2−ion in MgO

The electron-paramagnetic-resonance structure observed in the ${\mathrm{H}}^{2-}$ signal in thermochemically reduced MgO crystals has been analyzed and is shown to be due to the interaction with the ${}_{}{}^{25}{}_{}{}^{}\mathrm{Mg}$ isotopes of the MgO lattice. It supports a defect configuration comprising a proton with three electrons in the anion sublattice. The values of the interaction parameters are compatible with the previous ground-state calculations.