Comparative Study of LiInSe2 Single Crystals for Thermal-Neutron Detection

Crystallography Reports - Two LiInSe2 single crystals, grown under different conditions, have been studied. Characteristics of these crystals for neutron detection have been compared using...     

Photoluminescence of Ge(Si)/Si(0 0 1) self-assembled islands in the near infra-red wavelength range

The dependence of photoluminescence spectra of structures with GeSi/Si(0 0 1) self-assembled nanoislands on growth temperature has been investigated. It was shown that the redshift of the island-related photoluminescence peak with a decrease of the growth temperature is associated with suppression of Si diffusion in the islands and an increase of Ge content in them. For the first time a photoluminescence signal from SiGe islands was observed at energies much lower than the Ge band gap. The energy position of the island-related photoluminescence peak is well described by the model of optical transition, which is indirect in real space. The photoluminescence signal at 1.55 μm from GeSi/Si(0 0 1) self-assembled islands was obtained up to room temperature.     

Hybrid Parametric Solitons in Nonlinear Photonic Crystals

We analyze the characteristics of a three-frequency spatial parametric soliton formed by virtue of the cascade frequency tripling in quadratic, periodically poled crystals. A variational approach and a method of averaging are developed, which make it possible to describe analytically, with good accuracy, the characteristics of the spatial solitons studied numerically.     

Degradation of Metal 2-Acrylamido-2-methylpropanesulfonate-N-Vinylpyrrolidine Copolymers in Aqueous Solutions Containing Different Cations

The influence of single- and double-charged cations on degradation of metal 2-acrylamido-2-methylpropanesulfonate-N-vinylpyrrolidine copolymers in aqueous solutions in the presence of potassium peroxodisulfate, K₂S₂O₈, at 50 and 70°C was studied by viscosimetry.     

Crystal-chemical features of monoclinic lanthanide oxobromotungstates of composition LnWO4Br (Ln = Eu, Gd, Dy, Er, Yb)

The crystal-chemical properties of lanthanide oxobromotungstates of composition LnWO₄Br (Ln = Eu, Gd, Dy, Er, Yb) are studied. The crystal system and space group for the oxobromotungstates are determined. The unit cell parameters are refined. The parameters a, b, c, and V of the LnWO₄Br compounds are studied as functions of the atomic number of the lanthanide. Analytical equations are derived to predict unit cell parameters for unsynthesized lanthanide oxobromotungstates of the class in question.     

Effect of Low-Molecular-Weight Cationic Praestols on the Efficiency of Water Pretreatment at Heat and Electric Power Plants

The efficiency of water pretreatment at heat and electric power plants using low-molecular-weight cationic Praestols (coagulants) in combination with lime, iron sulfate, and flocculant (high-molecular-weight anionic Praestol) was studied.     

Spectrum and polarization of electrons in neutron beta-decay in an electromagnetic wave field

A study is made on a polarized neutron undergoing -decay induced by an intense electromagnetic wave. The angular distribution of electrons in the decay is obtained and their polarization is studied. A comparison is made with the decay of a moving neutron.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 33–37, March, 1987.The authors are grateful to L. I. Lapidus, B. K. Kerimov, and G. A. Chizhov for their interest in this work and for their constructive criticism.     

Quantum-chemical interpretation of the difference in the field fragmentation of the molecular ions of dimethyl ether and dimethyl sulfide

The potential energy surfaces (PES) of the positive molecular ions of dimethyl ether and dimethyl sulfide were scanned by the LCAO-MO SCF method in the MINDO/3 valence approximation. On the PES of these radical-cations, apart from the minima corresponding to the equilbrium structures, each has a local minimum which belongs to a cyclic structure. The discovered differences in the stereochemical construction of the cyclic structures of the radical-cations (CH₃)₂O⁺'and (CH₃)₂S⁺' made it possible to explain features of the field fragmentation of their molecular ions. The effect of the external electric field of the ion source on the cyclization and fragmentation stages in the investigated radical-cations was traced.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 25, No. 1, pp. 76–82, January–February, 1989.     

Copolymerization of acrylamide with sodium 2-acrylamido-2-methylpropanesulfonate in aqueous-alcoholic solutions

The effect of solvents on the kinetics of synthesis and molecular properties of copolymers formed by radical copolymerization of acrylamide with sodium 2-acrylamido-2-methylpropanesulfonate in water and in methanol-water (75: 25, 50: 50, 25: 75), ethanol-water (50: 50), and isopropanol-water (50: 50) solutions in the presence of potassium persulfate initiating agent at pH 9 and 60°C was studied.