Paramagnetic Resonance and Optical Absorption of aVCenter

The paramagnetic resonance and optical absorption spectra of KCl and KBr crystals containing divalent calcium, strontium or barium ions have been investigated. After x-irradiation at 195°K a resonance spectrum is observed with three distinguishable centers; the centers are similar and each has approximate axial symmetry about a different cube edge. The optical spectra show bands near 325 mμ in KCl and near 345 mμ in KBr which arise from the same centers. The centers are assigned to ${\mathrm{Cl}}_2^{-}$ and ${\mathrm{Br}}_2^{-}$ molecule ions and are closely related to the ${\mathrm{Cl}}_2^{-}$ and ${\mathrm{Br}}_2^{-}$ centers of Castner and Känzig.