Observation of the dielectric local mode related to divacancies in p-silicon

A dielectric local mode related to the motion of divacancies in p-silicon has been observed for the first time. The mode manifests itself in Fano-resonance signals in the photoconductivity spectra. We explain the behavior of the corresponding segment in these spectra caused by temperature variations. In light of the new results, we examine the entire set of the experimental facts related to positively charged divacancies: the high values of the cross sections of capture and photoionization of a hole at a single divacancy, the difference in the defect environment of electron and hole silicon, and the quadratic dependence of the concentration of defects containing divacancies on the intensity of the electron flux producing these defects. Zh. éksp. Teor. Fiz. 112, 707–713 (August 1997)     

Noncatalytic Regio- and Stereoselective Addition of Secondary Phosphines to Cyanoacetylenic Alcohols

Secondary phosphines regio- and stereoselectively add to 4-hydroxy-4-methyl-2-pentynenitrile, a typical and available representative of cyanoacetylenic alcohols, without catalyst at room temperature (THF, 3 h) to form (Z)-3-[dialkyl(aryl) phosphino]-4-hydroxy-4-methyl-2-pentenenitriles in 80–85% yields. These compounds relate to a new class of functionalyzed phosphines, promising ligands for the design of metal-complex catalysts.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 552–555.Original Russian Text Copyright © 2005 by Arbuzova, Shaikhutdinova, Gusarov, Nikitin, Mal’kina, Sukhov, Bogdanova, Trofimov.     

Elastic waves in a fiber-reinforced composite

The propagation of time-harmonic elastic waves in a fiber-reinforced composite is studied. The circular fibers are assumed to be parallel to each other and randomly distributed with a statistically uniform distribution. The direction of propagation and the associated particle motion are considered to be normal to the fibers. It is shown that the average waves in the composite separate into compressional and shear types. General formulae for the complex wave number giving the phase velocity and the damping are obtained. It is shown that these formulae lead to the Hashin-Rosen expressions for the transverse bulk modulus and the lower bound for the transverse rigidity, if the correlation in the positions of the fibers can be ignored. The correlation terms, for exponential correlation, are shown to have a significant effect on the damping property of the composite, especially at high frequencies and concentrations.     

Sorptive separation of molybdenum(VI) from rhenium-containing solutions

It is shown that Purolite S957 cation-exchange resin containing phosphonic-acid and sulfonic groups is capable of selectively sorbing molybdenum(VI) in the presence of rhenium(VII) in solution.     

Transition metal catalysed dehydrogenation of amine-borane fuel blends

Mixtures containing ammonia-borane and sec-butylamine-borane remain liquid throughout the hydrogen release process that affords tri(N-sec-butyl)borazine and polyborazylene. Concentrated solutions with metal catalysts afford >5 wt% H(2) in 1 h at 80 °C and addition of (EMIM)EtSO(4) ionic liquid co-solvent eliminates competing formation of insoluble linear poly(aminoborane) (EMIM = 1-ethyl-3-methyl-imidazolium).     

On the interaction of two beating electrostatic waves with plasma electrons

This paper is devoted to the study of the interaction of particles with two beating plasma waves. We follow the instructional article by Ott and Dum. According to them, the sum of wave actions during the interaction is constant, supposing the effect of trapped particles on the beat can be neglected. In the present paper, this problem is solved more generally, just for the case of trapped and also untrapped particles in the wave. Our study shows that the sum of wave actions is constant also in the case when the influence of the trapped particles on the amplitudes of two waves was considered. On the contrary this conclusion is not valid if it is supposed that two original waves are amplitude modulated e.g. by the influence of the interaction of the beat with particles. The author is deeply indebted to Dr. Ladislav Krlín for guidance and encouragement throughout the course of this work.     

Effective relaxation time of the impurity concentration in a medium with a slightly nonuniform diffusion coefficient

Based on the previously introduced integral criterion and a new approach to estimating the time characteristics of diffusion, the relaxation time of impurity concentration in a medium with a slightly nonuniform diffusion coefficient is determined. The diffusion coefficient profile that cuts the relaxation time is found.     

Study of the cation distribution in the surface layer and bulk of substituted iron garnet films

A comparative analysis has been carried out of the physical-chemical state of the surface and bulk of single-crystal films of the iron garnet Y_2.6Sm_0.4Fe_3.7Ga_1.3O₁₂ on substrates consisting of a gadolinium-gallium garnet single crystal. To carry out this study, we used the method of simultaneous γ-ray, x-ray, and electron Mösbauer spectroscopy, which made it possible to simultaneously extract information from the surface layers and the bulk of the sample. This method was applied using a precision system for the motion for the Mössbauer source. It is shown that the parameters of the hyperfine interactions in the surface layer and in the bulk of the film differ, and that these differences increase towards the surface. This result is explained by the fact that the surface layer is formed as the substrate, together with the synthesized film, is removed from the flux and, consequently, the temperature conditions of synthesis of the bulk and of the surface layer are different.     

A survey of symmetry point groups and characters of its irreducible representations

In this paper the character tables of irreducible representations of discrete symmetry point groups of general order are arranged.