Luminescence centers in Pb2Bi6O11 and Sn2Bi6O11 ceramics

We have studied the luminescence spectra and luminescence excitation spectra of Pb₂Bi₆O₁₁ and Sn₂Bi₆O₁₁ ceramics at 80 K. We have used the Alentsev-Fock to decompose the spectra into elementary components. We have established that the luminescence spectra of Pb₂Bi₆O₁₁ and Sn₂Bi₆O₁₁ ceramics contain three elementary bands each with maxima at 2.60, 2.32, 12.93 eV and 2.62, 2.30, 2.00 eV. Comparison of the data obtained with the results of a study of the luminescence spectra for a series of bismuth-containing oxide compounds suggest that luminescence of Pb₂Bi₆O₁₁ and Sn₂Bi₆O₁₁ is due to radiative processes in structural complexes containing a bismuth ion in a nearest-neighbor oxygen environment. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 597–600, September–October, 2006.     

Luminescence centers in thin films of lead and bismuth tungstates

Luminescence spectra of thin films of PbWO₄ and Bi₂WO₆ are invesigated. The Alentsev-Fock method is used to separate the spectra into elementary components. The emission bands with maxima at 2.8 eV in PbWO₄ and at 2.93 eV in Bi₂WO₆ luminescence spectra are interpreted as the emission of self-localized Frenkel excitons. The bands with maxima at 2.35 and 1.75 eV in PbWO₄ and at 2.35 and 1.9 eV in Bi₂WO₆ are related to oxygen vacancies. L’vov State University, 50, Dragomanov St., L'vov, 290005, Ukraine. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 1, pp. 143–145, January–February, 1998.     

Preparations and reactions of 2-trifluoromethylketenimines

Preparations and reactions of a series of 2-trifluoromethylketenimines are described. Trifluoromethylketenimines were prepared from trifluoropropanoic acids via corresponding imidoyl chlorides in good yields. 2-Trifluoromethylketenimine was functionalized at its β-position by electrophilic addition of halide, followed by dehydrohalogenation. Addition of nucleophile at α-position gave trifluoroethylated β-amino acid derivative via 1,3-proton shift.     

Halide ion determination from luminescence of the diprotonated form of porphyrin

We have studied quenching of the fluorescence of the diprotonated form of 3,7,13,17-tetramethyl-2,8,12,18-tetrabutylporphyrin by iodide ions in solutions. We have established that there is both static quenching of fluorescence when nonfluorescent complexes are formed with the iodide ions, as a result of an internal heavy atom effect, and also dynamic diffusion-controlled quenching. Based on analysis of the dependences of the fluorescence intensity and fluorescence lifetime on the iodide ion concentration in solution, we suggest using the diprotonated form of this porphyrin as the base compound for designing a fluorescent molecular receptor for halide ions. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 6, pp. 750–755, November–December, 2007.     

层状钙钛矿La1.3Sr1.7Mn2-xCuxO7的磁性及电特性

通过固相反应烧结法成功制备了层状钙钛矿La_1.3Sr_1.7Mn_2-xCu_xO₇多晶，主要研究了其磁电特性.结果表明，样品为Sr₃Ti₂O₇型钙钛矿结构.随着温度的降低，其磁性经历了一个很复杂的转变过程.当x=0时，在T^*=231K出现二维短程铁磁有序，在<     

Synthesis and characterization of a novel chiral azomethine diselenide

The first chiral diselenide 9 having an ortho-azomethine functional group has been synthesized by the reaction of bis(o-formylphenyl) diselenide with the chiral amine R(+)-(1-phenylethylamine). The chiral diselenide 9 was further characterized by derivatizing it into the corresponding selenenyl halides. The derivatives are characterized by single crystal X-ray diffraction studies. In the solid state, the bromide derivative 11 shows the strongest Se?N intramolecular interaction. The chiral azomethine diselenide 9 has been further reduced to afford the diselenide 13. The monoselenide analogues of 9 and 13 have also been synthesized.     

Development of Methods for the Production of Electrodes of Nonstoichiometric Compositions for Solid-Electrolyte Sensors with Predictable Sensitivity

The feasibility of application of sensor Me|Pb|PbCl₂-CaCl₂|Pb_{1 ± δ}|Me, where X = Se, Te, in an analysis of lead-containing gaseous environment is considered. The effect of the nature of the material, its nonstoichiometry, and the defect structure of measuring electrodes on the operation characteristics of these sensors is discussed. The mechanism of the formation of defects during the insertion of an electrochemically active component into the material of the measuring electrode is refined. The limiting stage of a process of a gas analysis is determined.__________Translated from Elektrokhimiya, Vol. 41, No. 6, 2005, pp. 728–734.Original Russian Text Copyright © 2005 by Leushina, Makhanova, Orzhaeva, Zlomanov.Published on the basis of a contribution delivered at the VII Meeting on Fundamental Problems in Solid-State Ionics (Chernogolovka-2004).     

The trapping effect of sulfur sensitization center Ag<Subscript>2</Subscript>S cluster on T-grain AgBrI microcrystals

The microwave absorption dielectric-spectrum technique was used to study the decay kinetics of photoelectrons in sulfur-sensitized silver halide crystals. The time-resolution spectrum of free electrons and shallow-trapped electrons generated in sulfur-sensitized AgBrl crystals has been obtained. The relationship of the trapping effect of sensitization centers Ag₂S and sensitization time or temperature in emulsions has been duscussed. With the increase in the sensitization time and temperature, the trap effect of sulfur sensitization centers varies from hole trap to shallow electron trap, and deep electron trap.