Knowledge Bank

Low temperature absorption spectra for $Re4+,ad3$ system, in various ($NR4)2SnCl6(R=CH3,C2H5,C3H7$) host crystals indicate effects of reduced host symmetry and origin shifts. In the $N(C2H5)4\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ and $N(C3H7)4\mathrm{<mrow\; data-mjx-texclass="ORD">+</mrow>}$ containing host crystals, a significant splitting as found that correlated to two substitutional sites with paralleling vibronic parterns. For $ReCl6\mathrm{<mrow\; data-mjx-texclass="ORD">2-</mrow>}$ in ($NR4)2SnCl6(R=H,CH3,C2H5,C3H7$), several new transitions located from 16000 to $20000cm-1$ were found using absorption and excitation spectroscopy, which cannot be assigned to intra-configurational transitions of $ReCl6\mathrm{<mrow\; data-mjx-texclass="ORD">2-</mrow>}$. These may be due to either impurity or interconfigurational transitions. Discussion of these unassignable transitions will be presented.