| THE EMISSION SPECTRA FOR THE Cs2NaScCl6:MoCl63- SYSTEM IN THE Fm3m SPACE GROUP |
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R. Acevedoa, T. Meruaneb and G. Navarroc aFacultad de Ciencias Fisicas y Matematicas, Universidad de Chile Beaucheff, 850, Casilla, 2777, Santiago, Chile bDepartamento de Quimica, Universidad Metropolitana de Ciencias de la Educacion Av. J.P. Alessandri, 774, Casilla 174-C, Santiago, Chile cComision Chilena de Energia Nuclear, Amunategui 95, Casilla, 188-D, Santiago, Chile |
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| Received: April 20, 2000; revised version December 27, 2000 |
| 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: Γ8(2T2g) -> Γ8(4A2g, Γ8(2Eg), Γ8(2T1g), Γ6(2T1g) for the Cs2NaScCl6:MoCl63- system in the Fm3m-space group. The experimental data available refer to the visible and near infrared luminescence spectra of MoCl63- complex ion in different hosts, such as Cs2NaMCl6 (M = Sc, Y, In), measured between 15,000cm-1 and 3,000cm-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 ν3(τ1u: stretching) of the MoX63-, complex ion and that of the host when M = In, Y. Thus for M = Sc, the slighter higher host ν3, wave number is likely to minimize the effect of this coupling. This evidence will allow us for the Cs2NaScCl6:MoCl63- 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. |
| DOI: 10.12693/APhysPolA.99.233 PACS numbers: 32.70.Fw, 32.70.Cs |