Métodos vibrónicos generalizados aplicaciones a sistemas del tipo elpasolitas estequiométricas Cs₂NaErCl₆

In this review, we study from an experimental and theoretical viewpoint, the advantages and disadvantages of the current vibronic models so as to estimate the spectral intensities associated with luminescence spectra of high resolution excitations at low temperature. This work is carried out with reference to the elpasolite type system Cs₂NaErCl₆. Experimental data is reported in the current research work, regarding oscillator strengths and relative vibronic intensity distributions for some selected electronic excitations such as Γ₁ → Γ₂ + v_k. These values are compared with those of that obtained by means of generalized vibronic theoretical methods such as the vibronic crystal field-ligand polarization and the superposition models due to Newman. A careful analysis is performed so as to estimate the role played when neglecting the coupling between the internal and the external vibrations for this system. The emissions considered throughout the course of this work are {|( ⁴S_3/2) Γ₈, |(⁴I _13/2) Γ_l → |(⁴I_15/2) Γ_k}. It is interesting to observe the quality of the results given when the vibronic crystal field-ligand polarization model is employed (VCF-LP). Our calculation method is based upon a minimum set of radial parameters and a generalized version of the valence force field to modulate the short range interactions. It is shown that this appoach is both flexible and useful to deal with these complex systems. We also analyze the theoretical and the experimental basis for a more realistic model and calculation method to carry out calculations for the lattice dynamics of these the stoichiometric elpasolite systems.