Abstract
The analysis of the Stark structure of multiplets of the ion Pr 3+ in the Cs2NaPrCl6, Cs2NaYCl6, Cs2NaYBr6 crystal systems is performed in the approximation of the weak and anomalous strong configuration interaction. The calculations in the approximation of the anomalous strong configuration interaction let considerably improve the description of the Stark structure of multiplets and thus provide an opportunity to estimate covalence parameters on the basis of experimental data on the Stark structure. Covalence parameters (the parameters of distribution of electronic density) obtained this way are well conformed to the parameters calculated by means of microscopic models.
Highlights
IntroductionCubic elpasolite crystals are appropriate for investigating the optical spectra and the lanthanide 4fN electronic state structure
Cubic elpasolite crystals are appropriate for investigating the optical spectra and the lanthanide 4fN electronic state structure.The concept of a crystal field is the key in the description of the experimental data of Stark splitting of multiples of ions with the empty f-shell.Fundamental spectroscopical properties of lanthanoids were considered in extensive monographs [1,2,3] in which various approaches in the description of the crystal systems activated by 4f-elements are described.The results of researches of optical properties of tervalent lanthanoids are given in work [4]
There are parameters ∆ci corresponding to the energy of the configuration with a charge transfer, and parameters of the covalence γσf and γπf (8) appear in the approximation of the anomalous strong configuration interaction (6)
Summary
Cubic elpasolite crystals are appropriate for investigating the optical spectra and the lanthanide 4fN electronic state structure. The accidental coincidences are almost excluded, the disadvantages of the theory are more obvious In connection with this in the articles [24,25,26] it is offered to use the spin-correlated crystal field Hamiltonian for the improvement of the description of Stark structure and the authors of the articles [30,31,32] suggest to perform calculations taking into account the influence of an excited 4 f N np -configuration. Both methods have allowed to improve considerably the description of experimental results. The considered theory allows to receive the parameters of distribution of electronic density (covalence parameters) on the basis of the description of Stark levels
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