[en] Photoluminescence (PL) spectra of Eu(III) and Tb(III) complexes with mixed oxydiacetate (ODA) and 1,10- phenanthroline (phen) ligands and with homoleptic ODA reveal characteristic line-splitting at 10 K, depending on the site-symmetry of the lanthanide ion in the complex. The energy-level schemes of the ⁷F_J states and the emitting levels for Eu(III) and Tb(III) ions have been proposed by simulating the line splitting in the framework of crystal-field Hamiltonian. The sets of refined crystal-field parameters for the experimentally determined sitesymmetry satisfactorily reproduce the experimental energy-level schemes. In addition, the PL quantum yield and the decay time were determined at room temperature. The PL quantum yields of [Eu(ODA)·(phen)·4H₂O]⁺ and [Tb(ODA)·(phen)·4H₂O]⁺ in the crystalline state (Q = 17.7 and Q = 56.6%, respectively) are much greater than those of [Eu(ODA)₃]^3- and [Tb(ODA)₃]^3- (Q = 1.1 and Q = 1.3, respectively), due to the energy transfer from phen to the lanthanide ion. In the aqueous state, the relaxation of the phen moiety due to the solvent results in the reduction of the quantum yield and the shortening of the lifetime

[en] The emission from KCl:Bi³⁺ excited in the X absorption band (i.e. between the A and B absorption bands) was measured as a function of temperature. The polarized emission spectrum and the angular dependence of polarization ratio were also investigated. The X-band excitation produces two emission bands peaking at 345 and 395 nm, the centres of which are not the same. The loosely bonded Cl^- ion arising from the substitution of Bi³⁺ ions into the KCl lattice is assumed to be the colour centre for the X-band emission. The definitive assignment of the two emission bands is presented in terms of the relaxed excited states of the perturbed Cl^- ion, in which the Jahn-Teller interaction coupling to the B₁ and B₂ vibronic modes is taken into account. (Author)

[en] A red phosphor composed of Y₂O₃:Eu³⁺ was coated with In₂O₃ by immersing the phosphor into either an ethanol or aqueous solution of InCl₃ precursor with subsequent heat annealing. The morphology of the coating depended on the solvent used in the precursor solution. Precursor deposition from ethanol resulted in partial coverage of the phosphor surface by In₂O₃ nanoparticles; the use of an aqueous solution resulted in multilayered In₂O₃ thin films. Aging effects of the uncoated phosphor during excitation were profound; the CL intensity decreased by about 94% after 2000 s, presumably due to surface charging of the phosphor induced by high-energy electron bombardment. The CL intensity of both uncoated and coated phosphors was measured at excitation voltages between 10 and 17 kV. The In₂O₃ nanoparticles were very effective at stabilizing and enhancing the CL intensity, even at sub-monolayer coverage. In contrast, thin film coatings of In₂O₃ significantly reduced the CL intensity. From these results, the conclusion was drawn that surface modification of Y₂O₃:Eu³⁺ with In₂O₃ nanoparticles would significantly improve the luminance of FEDs operating at voltages above 10 kV

[en] A novel Er(III) complex with oxydiacetate and 1,10-phenanthroline was synthesized and its structure and luminescence properties were characterized. The complex of [Er(ODA)·(phen)·4H₂O]⁺ crystallizes in the monoclinic space group P2₁/n with a = 12.216(4) A, b = 16.680(2) A, c = 12.627(3) A, β = 108.30(2) .deg. , V = 2442.7(11) A³, Z = 4 and ρ = 1.841 g/cm³. When the complex is excited at the He-Cd 325-nm line, it produces two broad bands spanning the regions 350-650 nm and 1200-1650 nm. The emission band of the complex is characterized by a series of spectral dips in the visible emission profile. The complex exhibits sensitized near-IR emission via two kinds of energy transfers from phen to Er(III): nonradiative and radiative energy transfers

[en] In this study, we introduced bis(dimethylamino)(N,N'-diisopropyl-ethylenediamine) germanium (1) and bis (dimethyl-amino)(N,N'-di-tert-butyl-ethylenediamine) germanium (2) as novel ALD precursors and analyzed the ALD growth characteristics to obtain the best possible film properties. A 5-L three-neck flask was charged with 2.5 L of toluene, GeCl_4 (60 g, 0.28 mol) was added and then cooled to -15 to -20 .deg. C. the two precursors produced good-quality GeO_2 thin films via the ALD process. The ALD windows of bis(dimethylamino)(N,N'-di-isopropyl-ethylenediamine) germanium and bis(dimethylamino)(N,N'-di-tert -butyl-ethylene-diamine) germanium were established at 200–330 .deg. C with a growth rate of about 0.40 and 0.31 Å/cycle, respectively. ALD-type growth mode was verified by increasing the precursor pulsing time. Growth rate was saturated from 3.0 s. These films have considerable potential for industrial applications

[en] A poly(1-hexyl-3,4-dimethyl-2,5-pyrrolylene) (PHDP) was prepared and its luminescence in tetrahydrofuran (THF) was studied. When PHDP is excited by UV light, it produces very strong blue luminescence. The quantum yield of PHDP (Q = 36.9%) is much greater than that of the monomer, 1-hexyl-3,4-dimethylpyrrole (HDP) with Q = 0.61%. The principal luminescence of PHDP has a single decay component with ca. 1 ns, whereas the decay of HDP is complicated. The molecular structure and conformational behavior of HDP and the oligomers up to trimer have been also determined by ab initio Hartree-Fock (HF/6-31G**), density functional theory (DFT-B3LYP/6-31G**), and semiempirical (ZINDO) methods. According to the results of calculations, it is proposed that the enhanced quantum yield of the polymer PHDP results mostly from the π- conjugation between neighboring pyrrole rings

[en] The effect of substitution of Sr²⁺ by Mg²⁺ on the luminescence properties of (Sr_0.9-xMg_x)Si₂O₂N₂:0.1Eu²⁺ were investigated as a function of the concentration of Mg²⁺(x). The peak position of the yellowish green emission from (Sr_0.9-xMg_x)Si₂O₂N₂:0.1Eu²⁺ was invariant with x. However, the luminescence intensity was significantly affected by x. With increasing Mg²⁺ concentration, the intensity increased to a maximum at x = 0.1. Partial substitution of Sr²⁺ by Mg²⁺ enhanced the intensity 1.8-fold. The Eu²⁺ concentration affected the peak positions of both luminescence and excitation. With increasing Eu²⁺ concentration, the red-shifting and enhancement of the luminescence were associated with the nephelauxetic effect. Concentration quenching of the luminescence occurred above y = 0.07 in the (Sr_0.8-yMg_0.1)Si₂O₂N₂:yEu²⁺. Above the critical concentration of Eu²⁺, non-radiative transitions between adjacent Eu²⁺ ions were more effective than the nephelauxetic effect. Optimized (Sr_0.83Mg_0.1)Si₂O₂N₂:0.07Eu²⁺ phosphors were fabricated with blue GaN LED and the chromaticity index of the phosphor-formulated GaN LED was investigated as a function of the wt% of the optimized phosphor. (copyright 2013 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

[en] Crystal structures of lanthanide complexes with NTA (NTA = nitrilotriacetate) are reported. The complexes of [Ln(NTA)_2·H_2O]"3"- (Ln = Sm, Eu, Gd, Tb and Ho) crystallize in the orthorhombic space group Pccn. In the structures, the trivalent lanthanide ions are completely encapsulated via coordination to the two nitrogen atoms and the six carboxylate oxygen atoms of the two NTA ligands, and one water oxygen atoms. The complexes form a slightly distorted capped-square-antiprism polyhedron. Of the complexes, [Eu(NTA)_2·H_2O]"3"-, [Tb(NTA)_2·H_2O]"3"- and [Dy(NTA)_2·H_2O]"3"- excited at the 325 He-Cd line produce very characteristic luminescence features, arising mostly from the f → f transitions. The absolute quantum yields of these complexes are determined at room temperature. Surprisingly, the [Dy(NTA)_2·H_2O]"3"- complex is more luminescent than the [Eu(NTA)_2·H_2O]"3"- and [Tb(NTA)_2·H_2O]"3"- complexes

[en] Laser-induced fluorescence was applied for the detection of lanthanide ions such as Tb³⁺ and Sm³⁺ in a pyrochemical processing. The fluorescence signals of Tb³⁺ and Sm³⁺ in LiCl-KCl molten salts were successfully observed at room temperature. Moreover, the fluorescence method was identified to be sensitive enough to detect a trace of Eu²⁺, originated from a reduction of Eu³⁺ contained in a LiCl-KCl eutectic reagent at a given high temperature molten salt condition. The non-destructive and direct fluorescence measurement can be an alternative method in on-line and in situ determination of the species and concentrations of lanthanides in a molten salt along with absorption measurement. (author)

[en] Two novel complexes of Sm(III) and Dy(III) with mixed oxydiacetate (ODA) and 1,10-phenanthroline (phen) ligands were synthesized and their structure and luminescence properties were characterized. The complexes of [Ln(ODA)(phen).4H₂O]Cl.5H₂O [Ln=Sm and Dy] crystallize in the monoclinic space group P2₁/n with Sm: a=12.3401(14) A, b=16.821(2), c=12.6847(11) A, β=107.939(10)^o, V=2505.0(5) A³, Z=4 and ρ=1.841 mg/m³, and with Dy: a=12.289(7) A, b=16.805(6) A, c=12.705(4) A, β=108.144(18)^o, V=2493.4(19) A³, Z=4 and ρ=1.786 mg/m³. The complexes of [Sm(ODA)(phen).4H₂O]⁺ and [Dy(ODA)(phen).4H₂O]⁺ excited by UV light produce orange red and lightly white emissions, respectively, via the nonradiative energy transfer from phen to the metals. The quantum yield of the sensitized luminescence of [Dy(ODA)(phen).4H₂O]⁺ (Q=19%) is much greater than that of [Sm(ODA)(phen).4H₂O]⁺ (Q=1.4%). The luminescence decay times of the complexes were in a few microsecond range and independent of temperature