Luminescence of europium trifluoroacetates

The luminescence spectral characteristics of mixed-ligand europium trifluoroacetates with nitrogen- and phosphorus-containing neutral ligands were studied at different temperatures. For several trifluoroacetates, the intensity of luminescence increased with temperature. The diffuse reflectance data were analyzed, and a mechanism of thermal luminescence buildup was suggested. Original Russian Text ? I.V. Kalinovskaya, A.N. Zadorozhnaya, A.G. Mirochnik, V.E. Karasev, 2009, published in Zhurnal Fizicheskoi Khimii, 2009, Vol. 83, No. 6, pp. 1175–1177.     

Crystal structure and triboluminescence of the [Eu(TTA)2(NO3)(TPPO)2] complex

The crystal structure of [Eu(TTA)₂(NO₃)(TPPO)₂] (I) (TTA = thenoyltrifluoroacetone, TPPO = triphenylphosphine oxide) possessing intense triboluminescence was established by X-ray crystallography. The crystals are triclinic, noncentrocymmetrical: a = 11.047(3) Å, b = 11.794(3) Å, c = 12.537(3) Å; α = 102.635 (4)°, β = 102.088(4)°,γ = 117.765(3)°; space group P1, Z = 1. The central Eu(III) atom coordinates two oxygen atoms of two TPPO molecules at distances of 2.271 Å and 2.282 Å, two oxygen atoms of the nitrate group at distances of 2.478 Å and 2.481 Å, four oxygen atoms of two TTA ions at distances of 2.365 Å, 2.381 Å, and 2.363 Å, 2.371 Å (coordination number is 8). The coordination polyhedron of the Eu(III) atom is a distorted dodecahedron. Possible reasons for spectral differences in the Stark structure of photo-and triboluminescence of I are discussed.     

Hall quantum Hamiltonians and electric 2D-curvature

For the Dirac 2D-operator in a constant magnetic field with perturbing electric potential, we derive Hamiltonians describing the quantum quasiparticles (Larmor vortices) at Landau levels. The discrete spectrum of this Hall-effect quantum Hamiltonian can be computed to all orders of the semiclassical approximation by a deformed Planck-type quantization condition on the 2D-plane; the standard magnetic (symplectic) form on the plane is corrected by an ??electric curvature?? determined via derivatives of the electric field. The electric curvature does not depend on the magnitude of the electric field and vanishes for homogeneous fields (i.e., for the canonical Hall effect). This curvature can be treated as an effective magnetic charge of the inhomogeneous Hall 2D-nanosystem.     

Sizing of particles levitating in a glow discharge dusty plasma

The dust particle size distribution in a volume glow discharge dusty plasma is studied. Polydisperse quartz particles are used as a dust component. It is found that a dusty plasma forms in a glow discharge not only in a dust trap but also near the wall at the bottom of the discharge chamber. Dust objects in the latter region are large: they contain up to 30000 particles. The size of particles levitating in discharge striations is three times larger than that of particles levitating near the wall. The idea of using the glow discharge dusty plasma for particle-size fractionation of polydisperse powder is put forward.     

Carboxylato-bis-dibenzoylmethanates of europium(III): Luminescence and magnetic properties

The luminescent and magnetic properties of europium(III) carboxylates, determined from the structure of Stark and Zeeman sublevels, are studied. It is found that the values of the λ_lum energy gap between the ground state ⁷ F ₀ and ⁷ F ₁ term in the luminescence spectra and λ_magn obtained from magnetochemical measurements correlate well.     

Crystal Structure and Excimer Fluorescence of Some Benzoylacetonatoboron Difluorides: Stacking Factor

The comparative study of the crystal structures of benzoylacetonato- (1), p-toluylacetonato- (2) and p-ethylbenzoylacetonatoboron (3) difluoride was carried out. Correlation of the luminescence properties of the complexes 1–3 and their crystal structures was revealed. The excimer formation in these compounds occurred the most efficiently for the complexes 1 characterized by the formation of stacks of molecules, unlike the complex 3, where individual dimers behaved as excimer-forming centers. The maximal fluorescence intensity was observed for the complex 2, which had the highest structural ordering.     

The mechanochemical treatment of europium nitrate with 1,10-phenanthroline

The reactions that occur during the mechanochemical treatment of europium nitrate with 1,10-phenanthroline were studied by X-ray electron, infrared, and luminescent spectroscopy. Two minutes of mechanical activation resulted in the formation of europium nitrate, 1,10-phenanthroline, and water. According to the X-ray electron spectroscopy data, the coordination of 1,10-phenanthroline to europium nitrate was accompanied by a decrease in the Eu 4d _5/2 binding energy. Intense mechanochemical transformations caused changes in the composition of the surface of samples. Changes in the shape and size of reaction mixture particles and the morphology of sample surfaces after mechanical treatment in a ball mill compared with the initial mixture were studied.     

Morphological structure and dispersity of luminescent heteroligand europium cinnamates

The luminescence characteristics of heteroligand europium cinnamates are reported. As follows from the IR spectra, cinnamic acid coordinates with europium in these compounds in the bidentate fashion. The shape, size, and surface morphology of particles of heteroligand europium cinnamates were determined by scanning electron and atomic force microscopy. Heteroligand europium complexes usually form plate-like and needle-like microcrystals of size 0.1–15 μm.