Absorptions and Emissions for the TmCl$\text{}_{6}^{3-}$ Ion in Cs$\text{}_{2}$NaTmCl$\text{}_{6}$

In this work we report both experimental and theoretical studies regarding the Cs$\text{}_{2}$NaTmCl$\text{}_{6}$ elpasolite-type system, for which we have an updated database from linear and nonlinear optics. Both the absorption and the emission spectra for this system are rather complicated and a generalized vibronic crystal field-closure-ligand polarization calculation model has been employed to rationalize the observed spectral intensities. The calculation has been carried out by neglecting the interaction among the internal and the external vibrations and theoretical calculations have been performed with reference to both the emissions $\text{}^{3}$H$\text{}_{4}$(Γ$\text{}_{i}$)>$\text{}^{3}$F$\text{}_{4}$(Γ$\text{}_{j}$) and the absorptions $\text{}^{3}$H$\text{}_{6}$(A$\text{}_{1}$)> $\text{}^{3}$F$\text{}_{4}$(Γ$\text{}_{i}$), $\text{}^{1}$G$\text{}_{4}$(Γ$\text{}_{i}$), $\text{}^{3}$H$\text{}_{5}$(Γ$\text{}_{l}$) withΓ$\text{}_{k}$ (k=i,j)=A$\text{}_{1}$,E,T$\text{}_{1}$,T$\text{}_{2}$ andΓ$\text{}_{l}$=E, $\text{}^{a}$T$\text{}_{1}$, $\text{}^{b}$T$\text{}_{1}$,T$\text{}_{2}$. The advantages and disadvantages of our model calculation are discussed in the text, and despite the simplicity of the model it is shown that it has got some utility and flexibility to gain understanding in these complex phenomena.