Fluorescence properties of mixed-ligand europium carboxylates

Mixed-ligand binuclear and mononuclear europium carboxylate complexes with nitrogen-and phosphorus-containing neutral ligands have been studied by luminescence and X-ray photoelectron spectroscopy. The coordination of neutral ligands through the nitrogen donor atom leads to an increase in electron density at the Eu³⁺ atom. In groups of carboxylates of the same type, the coordination of neutral donor ligands leads to an increase in the relative intensity of the ⁵ D ₀-⁷ F ₄ electric dipole transition. Analysis of the luminescence excitation spectra points to the presence of two excitation energy transfer channels for mixed-ligand europium trifluoroacetate and toluate complexes and of one channel for europium cinnamate complexes with neutral ligands.     

Structural characterization of gentiobiosyl diglycerides fromBacillus pumilus associated with ascidiaHalocynthia aurantium

A mixture of 1(3),2-di-O-acyl-3(1)-O-β-gentiobiosylglycerols was isolated from a sea isolate ofBacillus pumilus. The components of the mixture were structurally characterized by mass spectrometry and¹H and¹³C NMR spectroscopy data for the native compounds and their derivatives. The predominant component contains two C₁₅ acyl groups, while the second component contains C₁₅ and C₁₇ fatty acids. Six minor components differ in residues of fatty acids and/or their combinations. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 166–170, January, 2000.     

Luminescent and photochemical properties of the lanthanide-containing polymer materials

The light-transforming polymer materials have been obtained based on the mixed europium cinnamates, cinnamic acid, and high density polyethylene. The materials exhibit an intensive luminescence in the range of 400–700 nm. The photostability of the materials has been higher than that of polymer materials activated solely with europium compounds. The photolysis of the luminescent polymers has been studied. For the obtained polymer compositions the build-up of europium ion and cinnamic acid luminescence has been observed.     

Mechanochemical synthesis of nanosized europium nitrate with 1,10-phenanthroline

Mechanochemically synthesized europium nitrate with 1,10-phenanthroline (Phen) is formed into globules with sizes of 100–300 nm, which are assembled into larger globular aggregates or packed into layers. The increasing mechanical activation time induces sintering, generating porous aggregates with micro-and nanopores. Eu²⁺ paramagnetic centers, detectable by ESR, are generated by mechanical grinding. Possibly, they are positioned on the surfaces of nanoglobules. The complex Eu(NO₃)₃ · 2Phen synthesized conventionally from aqueous ethanol consists of needle-shaped microcrystallites. They do not give rise to ESR spectra.     

The dispersity and distribution of luminophors in high-pressure polyethylene

Polymers based on high-pressure polyethylene were prepared and activated with europium(III) complexes with carboxylic acids and compositions based on europium-anthranilic acid compounds. According to the electron scanning, atomic, and fluorescence spectroscopic data, luminophor particles showed a heterophase distribution in films. The particles had an average size of 3–30 μm and were shaped as globules.     

The luminescent properties of polyethylene films with admixtures of luminophores based on europium compounds

Polyethylene films activated with europium(III) complexes with carboxylic acids and Eu(L)₃ · nD · xH₂O + ANT compositions, where L is the trifluoroacetic, toluyl, or cinnamic acid anion and ANT is anthranilic acid, were prepared. The intensity of luminescence of the polymeric compositions depended on the content of luminophores (molar ratio between europium compounds and anthranilic acid). An analysis of the excitation spectra showed that, in polymer—Eu(L)₃ · nPhen · xH₂O + ANT compositions, there was effective energy transfer from phenanthroline to anthranilic acid levels.     

Atomic parity-violation and precision physics

The atomic parity-violation (APV) parameter for a nucleus with n neutrons and z protons has been included in the list of pseudo-observables accessible with the codes TOPAZ0 and ZFITTER. In this way one can add the APV results in the LEP EWWG “global” electroweak fits, checking the corresponding effect when added to the existing precision measurements. Received: 8 March 2001 / Published online: 21 September 2001     

Electroweak radiative corrections to single top production

Fortran subroutines to calculate helicity amplitudes with massive spin-3/2 particles, such as massive gravitinos, which couple to the standard model and supersymmetric particles via the supercurrent, are added to the HELAS (HELicity Amplitude Subroutines) library. They are coded in such a way that arbitrary amplitudes with external gravitinos can be generated automatically by MadGraph, after slight modifications. All the codes have been tested carefully by making use of the gauge invariance of the helicity amplitudes.     

Luminescence of ytterium(III) β-diketonate complexes containing different ligands

The spectral and luminescent characteristics of ytterbium(III) β-diketonate complexes containing different nitrogen- and phosphorus-containing ligands are determined. The most intensive luminescence in the IR region is observed for the neutral phosphorus-containing ligands.     

Luminescence and magnetic properties of mixed-ligand europium trifluoroacetates

The luminescence and magnetic properties of mixed-ligand europium trifluoroacetates with nitrogen- and phosphorus-containing neutral ligands [Eu(TFA)₃ · 3H₂O]₂ and Eu(TFA)₃ · 2D · nH₂O were studied (here TFA is the trifluoroacetic acid anion, and D is Phen (1,10-phenanthroline), n = 1; DMF (dimethylformamide), n = 1; or TPPO (triphenylphosphine oxide), n = 3). The molar magnetic susceptibility increased in the series of complex compounds Eu(TFA)₃ · 2Phen · H₂O < [Eu(TFA)₃ · 3H₂O]₂ < Eu(TFA)₃ · 2DMF · H₂O < Eu(TFA)₃ · 2TPPO · 3H₂O. Correlations were found between the luminescent and magnetic characteristics of the complex compounds.