Knowledge Bank

Electronic d-d transitions within the $t2g\mathrm{<mrow\; data-mjx-texclass="ORD">4</mrow>}$ manifold of $Os4+$ doped into cubic host crystals of $Cs2ZrCl6$ and $K2PtCl6$ were observed at $4\circ K$ and $77\circ K$ by means of absorption and magnetic circular dichroism measurement. The $A1g(3T1g)\to T2g(1T2g),Eg(1Eg)$ transitions near $10000cm-1$ and the $A1g(3T1g)\to T2g,Eg(3T2g)$ transitions near $5000cm-1$ were studied. Due to the close proximity of the electronic states, the spectra in both regions consists of overlapping vibronic bands. At $3000cm-1$ the magnetic dipole allowed origin of the $A1g(3T1g)\to T1g(3T1g)$ was observed for the first time. By coupling hot band and vibronic analysis to the magnetic circular dichroism results, revised energy level assignments were made for these states. The experimental assignments were correlated with results from a complete ligand field calculation.