ABSORPTION AND MAGNETIC CIRCULAR DICHROISM SPECTRA OF $RE^{+}$ IN CUBIC HOST SYSTEMS

Abstract

Under the combined influences of a strong octahedral crystal field and a large spin-orbit interaction, the $t_{2g}{^{3}}$ configuration of $Re^{+4}$, a $5d^{3}$ ion, is split into the following states in order of increasing energy: $U_{g}^{\prime}(^{4}A_{2g}), U_{g}^{\prime} (^{2}T_{1g}), U_{g}^{\prime} (^{2}E_{g}), E_{g}^{\prime} (^{2}T_{1}g), E_{g}^{\prime\prime}(^{2}T_{2g})$ and $U_{g}^{\prime} (^{2}T_{2g})$. Electric dipole forbidden transitions between the $U^{\prime} (^{4}A_{2g})$ ground state and all these excited states have been observed directly for the first time in cubic crystals of $Cs_{2}ZrCl_{6}: Re^{+4}$ and $Cs_{2}ZrBr_{6}: Re^{+4}$ by means of low temperature absorption and magnetic circular dichroism (MCD) spectroscopy. The assignments are confirmed via a hot band analysis of the 77K absorption and MCD spectra. The experimental results will be compared to the results of a ligand field calculation.