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The Emission Spectra for the Cs_2NaScCl_6:MoCl_6^{3-} System in the Fm3m Space Group

100%

Acevedo R., Meruane T., Navarro G.

Acta Physica Polonica A

2001

vol. 99

issue 2

233-242

On the basis of the data reported by Flint and Paulusz, we have undertaken a theoretical investigation of the intensity mechanism for the various emissions:Γ_8(^2T_{2g} ) → Γ_8(^4A_{2g}), Γ_8(^2E_{g}), Γ_8(^2T_{1g}), Γ_6(^2T_{1g}) for the Cs_2NaScCl_6:MoCl_6^{3-} system in the Fm3m-space group. The experimental data available refer to the visible and near infrared luminescence spectra of MoCl_6^{3-} complex ion in different hosts, such as Cs_2NaMCl_6 (M = Sc, Y, In), measured between 15,000 cm^{-1} and 3,000 cm^{-1} at liquid helium temperatures. At least, five luminescence transitions have been identified and assigned and each of them show extensive vibronic structure. A careful analysis of this experimental data shows that for the various observed electronic transitions, the vibrational frequencies change only slightly, and therefore there is no indication that the system undergoes both a significant and relevant Jahn-Teller distortion (along an active coordinate). There is however clear evidence that for the chloro-elpasolites, there is a strong resonance interaction between ν_3(τ_{1u} : stretching) of the MoX_6^{3-}, complex ion and that of the host when M = In, Y. Thus for M = Sc, the slighter higher host ν_3, wave number is likely to minimize the effect of this coupling. This evidence will allow us for the Cs_2NaScCl_6:MoCl_6^{3-} system to neglect, in the first-order approximation, the coupling among the internal and the external vibrations and to proceed using a both a molecular and the independent system models.

Spectral Intensities for the Emission |^4S_{3/2}Γ_8〉 → |^4I_{15/2}Γ〉in the Cs_2NaErCl_6

88%

Acevedo R., Soto-Bubert A., Navarro G., Meruane T., Stręk W.

Acta Physica Polonica A

2004

vol. 105

issue 3

233-251

We report explicit vibronic intensity calculations for the |^4S_{3/2}Γ_8> → |^4I_{15/2}Γ>excitations in the Cs_2NaErCl_6 elpasolite-type systems, based upon new and updated experimental data, obtained from optical absorption measurements made at 10 K, in the energy range from 6,000 up to 26,000 cm^{-1}. Our calculation model is a generalization of the vibronic crystal field-ligand polarization method and the calculation is performed using a minimum set of adjustable parameters - all and each of them have a clear physical meaning. Our strategy was chosen so as to make a significant distinction with previous calculations, performed by other authors, who have worked out a model originated from a supra-parameterized scheme, within the framework of the superposition model of Newman. Throughout the course of the current work, it is shown that our model is suitable to handle this kind of calculations and also that the numerical results obtained are in fairly good agreement with experiment.

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2 Acta Physica Polonica A

1 2004

1 2001

2 Acevedo R.

2 Meruane T.

2 Navarro G.

1 Soto-Bubert A.

1 Stręk W.

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The Emission Spectra for the Cs_2NaScCl_6:MoCl_6^{3-} System in the Fm3m Space Group

Spectral Intensities for the Emission |^4S_{3/2}Γ_8〉 → |^4I_{15/2}Γ〉in the Cs_2NaErCl_6