Eu3+ complexes and specially β-diketonate compounds are well known and studied in several areas due to their luminescence properties, such as sensors and lightning devices. A unique feature of the Eu3+ ion is the experimental determination of the 4f-4f intensity parameters Ωλ directly from the emission spectrum. The equations for determining Ωλ from the emission spectra are different for the detection of emitted power compared to modern equipment that detects photons per second. It is shown that the differences between Ωλ determined by misusing the equations are sizable for Ω4 (ca. 15.5%) for several Eu3+β-diketonate complexes and leads to differences of ca. 5% in the intrinsic quantum yields Q_Ln^Ln. Due to the unique features of trivalent lanthanide ions, such as the shielding of 4f-electrons, which lead to small covalency and crystal field effects, a linear correlation was observed between Ωλ obtained using the emitted power and photon counting equations. We stress that care should be exercised with the type of detection should be taken and provide the correction factors for the intensity parameters. In addition, we suggest that the integrated intensity (proportional to the areas of the emission band) and the centroid (or barycenter) of the transition for obtaining Ωλ should be determined in the properly Jacobian-transformed spectrum in wavenumbers (or energy). Due to the small widths of the emission bands of typical 4f-4f transitions, the areas and centroids of the bands do not depend on the transformation within the experimental uncertainties. These assessments are relevant because they validate previously determined Ωλ without the proper spectral transformation.
Bond-length distributions have been examined for eighty-four configurations of the lanthanide ions and twenty-two configurations of the actinide ions bonded to oxygen. The lanthanide contraction for the trivalent lanthanide ions bonded to O<sup>2-</sup> is shown to vary as a function of coordination number and to diminish in scale with increasing coordination number.
Trivalent lanthanide ions form 1 : 1, 1 : 2, and 1 : 3 complexes with tridentate ligand TMDGA in 1 M H/NaNO3 and form 1 : 3 extracted complexes with DMDODGA during solvent extraction.
Synthesis process and luminescence properties of trivalent lanthanide ions (Ln3+) doped YF3 nanoparticles have been investigated. To synthesis Ln3+-doped YF3 nanoparticles, the mixture of (YCl3·nH2O + LnCl3·nH2O),
and NH4F was hydrothermal treated at 180 °C in a Teflon-liner auto-clave or heated at higher temperatures (400 °C ∼ 600 °C) in a stove. The XRD patterns showed that the Ln3+-doped orthorhombic YF3 nanoparticles with no second phase have been
prepared. The solid solution Y1−xEuxF3 (x = 0 ∼ 0.4) nanoparticles have been synthesized. The luminescence concentration quenching resulted from resonance energy transfer between neighboring Eu3+ ions occurred at higher
Eu3+ concentrations (30 mol%). The upconversion luminescence of Er3+−Yb3+ codoped YF3 nanoparticles under 980 nm excitation has also been observed. With increase of heated temperature, the size of the Er3+−Yb3+ codoped
YF3 nanoparticles increased gradually, and upconversion luminescence intensity increased significantly.
1-(2-Benzthyazolyl)-3-methyl-4-azo-(4-nitrophenyl)-Pyrazolyn-5-one (HL) possesses a chelating behavior. Its chelates with a number of trivalent lanthanide ions Pr(III), Sm(III),Gd(III), Ho(III), La(III) of the type Na3[Ln(L)2(OH)4] have been isolated and characterized on the basis of their elemental analyses, IR and visible spectra, magnetic and molar conductance studies, thermal and X-ray analysis and molecular weight determinations. All chelates have a monomeric octa-coordinated stn1cture and square antiprismatic (C2) symmetry.
Об экспериментальном определении параметров интенсивности 4f-4f-переходов по спектрам излучения соединений европия (III)