Experimental and theoretical studies of the vibrational and electronic spectra of a lanthanide ion at a Site of T h symmetry : Pr 3+ in Cs 2NaPr(NO 2) 6

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Author(s)

  • Wenyu Li
  • Lixin Ning
  • Michèle D. Faucher
  • Peter A. Tanner

Detail(s)

Original languageEnglish
Pages (from-to)9004-9013
Journal / PublicationInorganic Chemistry
Volume50
Issue number18
Publication statusPublished - 19 Sep 2011

Abstract

The Pr 3+ ion in Cs 2NaPr(NO 2) 6 is situated at a site of T h symmetry with 12-coordination to O atoms of bidentate nitrito groups. First-principles calculations of the vibrational modes of the complex were carried out using the density functional theory with the generalized gradient approximation Perdew-Burke-Ernzerhof exchange-correlation functional. The calculations that treated the Pr 3+ 4f electrons as valence electrons showed better agreement with the experimental vibrational assignments compared with those treating the 4f electrons a part of the inner core. The 1D 23H 4 emission spectra of Cs 2NaPr(NO 2) 6 at 7 K enabled assignments to be made for the crystal-field (CF) levels of the ground-state multiplet. The emission of the dilute system Cs 2NaY(NO 2) 6:Pr 3+ was dominated by NO 2 - triplet emission, which was quenched at elevated temperatures by energy transfer to trace Eu 3+ impurity. From magnetic dipole calculations and the vibronic fingerprint, detailed assignments are given for the complex 10 K electronic absorption spectrum of Cs 2NaPr(NO 2) 6 between 3940 and 18800 cm -1, and the derived Pr 3+ 4f 2 energy-level data set has been fitted by calculation. By comparison with Cs 2NaPrCl 6, the fourth-order CF parameter in Cs 2NaPr(NO 2) 6 is relatively small so that interaction with a 4fnp configuration is not important. From the NO 2 - absorption bands above 20 000 cm -1, the N-O bond length change upon excitation is small, whereas the angle O-N-O opens by more than 10° in the triplet state. By contrast to the NO 2 - internal vibration frequencies, which except for the wagging mode show only minor changes with the environment, the triplet-state energy shows a linear decrease with an increase of the lanthanide (Ln 3+) ionic radius in Cs 2NaLn(NO 2) 6. Using the eigenvectors from the energy-level fit, the variation of the inverse magnetic susceptibility with temperature has been calculated between 1 and 100 K and the values are somewhat lower than those from experiment. © 2011 American Chemical Society.

Citation Format(s)

Experimental and theoretical studies of the vibrational and electronic spectra of a lanthanide ion at a Site of T h symmetry : Pr 3+ in Cs 2NaPr(NO 2) 6. / Li, Wenyu; Ning, Lixin; Faucher, Michèle D.; Tanner, Peter A.

In: Inorganic Chemistry, Vol. 50, No. 18, 19.09.2011, p. 9004-9013.

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review