SHARP-LINE LUMINESCENCE OF $Os^{4+}$ AND $Re^{4+}$ IN SINGLE CUBIC CRYSTALS OF $Cs_{2}ZrC1_{6}$ AT $20^{\circ} K$

Author Institution: Departments of Chemistry and Physics, University of MaineStrong sharp-line luminescence has been observed for the 5d$^{4}$ $Os^{4+}$ion as an impurity in single cubic crystals of the host lattice $Cs_{2}ZrCl_{6}$ at $20^{\circ} K$. In the visible and near infrared regions luminescence occurs within the $t_{2g}^{4}$ configuration between the $\Gamma_{1}(^{1}A_{1{g}})$ excited electronic state at 17 069 $cm^{-1}$ and the four spin-orbit components of the $^{3}T_{1g}$ ground electronic state at 0, 2777, 4873, and 4972 $cm^{-1}$. Each of these transitions is rich in vibrational structure. The detailed vibronic structure has been assigned on the basis of a phonon density of states calculation and the Jahn-Teller effect. Similar results have been obtained for the 5d$^{3}$ $RE^{+4}$ ion