N. V. Vasil’eva

Effect of Pb ions on the optical absorption in Gd3Ga5O12 epitaxial films

We have studied the effect of Pb2+ impurities and Pb2+-Pb4+ pairs on the optical absorption between 200 and 860 nm in single-crystal gadolinium gallium garnet films grown by liquid-phase epitaxy from supercooled PbO-B2O3 fluxed melts containing 0.1–0.5 mol% gadolinia.

Luminescence of gadolinium garnet single crystals excited by synchrotron radiation

Single crystals of gadolinium-containing garnets with the compositions Gd3Ga5O12, Gd3(Sc,Ga)5O12:Cr, and (Gd,Ca)3(Mg,Zr,Ga)5O12 were grown using the Czochralski technique, and their luminescence was studied under the conditions of excitation with “white” synchrotron radiation. The observed differences in the luminescence spectra are discussed.

Effect of Al and Ce ion concentrations on the optical absorption and luminescence in Gd3(Al,Ga)5O12:Ce3+ epitaxial films

We have studied the effect of Al and Ce ions on the optical absorption and luminescence of singlecrystal (Pb,Gd)3–yCeyAlxGa5–xO12 (x = 2.02, 2.09, 2.13, 2.17, 2.22; y = 0.02, 0.06, 0.07) films grown on (111)-oriented single-crystal Gd3Ga5O12 substrates by liquid-phase epitaxy from supercooled high-temperature solutions using solvents of the PbO–B2O3 system and growth charges containing 2.0, 2.1, or 2.2 mol % aluminum oxide and 0.03 or 0.2 mol % cerium oxide. The shift of the absorption bands of the Ce3+ 5d1 and 5d2 levels has been determined as a function of Al concentration in the films. The intensity of the Ce3+ luminescence bands of the films has been shown to increase with increasing Al and Ce concentrations.

Effect of Gd2O3 concentration in Bi-containing high-temperature solutions on the luminescence of epitaxial Gd3Ga5O12 films

Single-crystal gadolinium gallium garnet films have been grown by liquid-phase epitaxy on (111) Gd3Ga5O12 substrates from supercooled Bi2O3-B2O3 fluxed melts at different Gd2O3 concentrations. The luminescence spectra of the films have been measured at 10 and 300 K under unmonochromatized synchrotron X-ray excitation and selective UV synchrotron excitation. The Bi3+ luminescence is discussed.

Electrochemical reduction of decafluorobenzil in DMF on a platinum electrode

The mechanism of electrochemical reduction of decafluorobenzil on a platinum electrode in DMF was investigated by cyclic voltammetry. The first reduction peak corresponded to a reversible single-electron transfer leading to the formation of a relatively stable anion-radical whose ESR spectrum was registered and characterized. The second peak corresponded to the reduction of the anion-radical into an unstable dianion that quickly reacted with initial decafluorobenzil, and the arising species (or its transformation product) at the given potential underwent further reduction. The effect of fluorine on the potentials and on the mechanism of the electrochemical reduction of decafluorobenzil was considered.

Spectral and luminescence properties of gadolinium gallium garnet epitaxial films doped with terbium

Gadolinium gallium garnet single-crystal films containing terbium are grown through liquid-phase epitaxy from a supercooled solution melt in the PbO-B2O3 system. The optical absorption spectra in the wavelength range 0.2–10.0 μm and the luminescence spectra excited by synchrotron radiation with energies in the range 3.5–30.0 eV are investigated at temperatures of 10 and 300 K. It is revealed that the optical absorption spectra contain an absorption band with the maximum at a wavelength λ ≈0.260 μm, which corresponds to the spin-allowed electric dipole transition between the electronic configurations 4f8(7F6) → 4f7(8S)5d of the Tb3+ ions. The narrow low-intensity absorption bands attributed to the 4f → 4f transitions from the 7F6 ground level to the 7F0–5 multiplet levels of the Tb3+ ions are observed in the wavelength range 1.7–10.0 μm. In the luminescence spectra measured at a temperature of 10 K, the highest intensity is observed for a band with the maximum at a wavelength λ ≈ 0.544 μm, which is associated with the 5D4 → 7F5 radiative transition in the Tb3+ ion.

Liquid-phase epitaxy and optical absorption of gadolinium-gallium garnet films grown from a PbO-B2O3 solution melt on Gd3Ga5O12 substrates

The optical absorption due to impurity ions was studied in gadolinium-gallium garnet single crystal films with a stoichiometric composition Gd3Ga5O12 grown by liquid-phase epitaxy from a supercooled PbO-B2O3 solution melt on (111)-oriented Gd3Ga5O12 substrates.

Characteristic features of ferromagnetic resonance in iron-garnet films with orthorhombic magnetic anisotropy

The characteristic features of ferromagnetic resonance (FMR) were studied in bismuth-containing single-crystal iron-garnet films (BSIGFs) with no rapidly relaxing ions and relatively weak orthorhombic magnetic anisotropy (ORMA). The films were grown on (110) and (210) substrates by liquid-phase epitaxy from a supercooled flux solution. Attention is focused mainly on the unidirectional magnetic anisotropy in the film plane and on the effect of the film/substrate transitional surface layer on the FMR spectrum.

Synthesis and electrochemical Reduction of 2,2′-diaryl-5,5,5′,5′-tetramethyl-3,3′-bi(pyrrol-3-ylidene)-4,4′(5H,5′H)-dione 1,1′-dioxides

Abstract2,2′-Diaryl-5,5,5′,5′-tetramethyl-3,3′-bi(pyrrol-3-ylidene)-4,4′(5H,5′H)-dione 1,1′-dioxides containing a carboxy, alkoxycarbonyl, or carbamoyl group in the para position of one or both benzene rings were synthesized. These compounds may be regarded as cyclic dinitrones with conjugated C=C bond. Mild aminolysis of carboxy groups in the title compounds may be used to introduce dinitrone fragments into oligonucleotide or polypeptide structures. Electrochemical reduction of the resulting amides involves reversible oneelectron transfer in the first step at a near-zero potential, which makes it possible to use the title compounds as electrochemically active labels in applied bioorganic electrochemistry.

Phosphorescence of a gadolinium gallium garnet single crystal

The phosphorescence of a Gd3Ga5O12 single crystal grown by the Czochralski method is discussed. The phosphorescence was excited by UV radiation of a deuterium lamp.