## Features of energy spectra and properties of polycrystalline Pb[1-x]Cd[x]Se films formed on calcium fluoride and glass substrates

Published in category «Condensed matter physics»

High-temperature treatment of films on the glass substrates creates composite films of main materials and dielectric phase in the oxygen-containing medium. In this case the concentration of free holes in the vicinity of the crystallites surface decreases and photoluminescence of films grows up. Annealing in iodide vapor leads to the appearance of photoconductivity and to sharp intensification of photoluminescence of films. The effects are explained by inversion of surface conductivity in PbSe crystallites because of formation of localized states having the donor character.

## The rectifying properties of C60 fullerene-based structures

Published in category «Condensed matter physics»

The structure, composition and electrical properties of the films produced by the vacuum evaporation method from amixture of C_{60} with organic or inorganic donor semiconductor were investigated. Diode current-voltage characteristics with arectification ratio, depending on the composition and structure of the films were found. A comparative study of the compositestructures was carried out, conclusions about the prospects of using a mixture of inorganic semiconductor with a fullerene to make a bulk heterojunction-based diode with a high rectification ratio were done.

## A change in incommensurate phase existence in (NaNO[2])[1-x](BaTiO[3])[x] ferroelectric composite

Published in category «Condensed matter physics»

The temperature and frequency dependences of dielectric properties of (NaNO_{2})_{1-x}(BaTi_{O3})_{x} ferroelectric composites have been studied. It was shown that in the composites as well as in solid solutions, the mutual influence of the components may lead to the expansion of incommensurate phase existence in NaNO_{2}. The greatest contribution to the low-frequency dielectric constant of the composite is due to the Maxwell-Wagner polarization.

## The technique of investigation of surface states in a sharp nonsymmetrical CdS / p-Si heterostructures

Published in category «Condensed matter physics»

The technique for determining the energy density of surface states in a sharp nonsymmetrical heterostructures, based on the measurement of high-and low-frequency capacitance-voltage characteristics, is presented. The technique can be applied in the case, where the charge of surface states depends on the voltage of a reverse bias. The results of investigation of theCdS/p-Si heterostructure produced by hydro-chemical deposition are presented.

## Reactor pressure effect on optical properties of MOVPE-grown InGaN heterostructures

Published in category «Condensed matter physics»

Influence of reactor pressure during MOVPE growth on optical properties of InGaN heterostructures has been studied. It was found that reactor pressure influences not only indium incorporation, but also strongly modifies optical properties of structures.

## The resistive switching effect in polymer materials and nonvolatile memory based on this effect

Published in category «Condensed matter physics»

Resistive switch effect in polystyrene has been investigated at room temperature and at the liquid helium temperature. Applied fields did not exceed 400 kV/cm, values of current density were less than 8 mA/mm^{2}. Stable, fast (down to 10 ns),multiple (up to 106 times) reiterative switches were fulfilled for creation nonvolatile resistive memory.

## Tightening of the soft mode in epitaxial thin films of relaxor ferroelectric materials

Published in category «Condensed matter physics»

The paper presents the results of inelastic scattering of synchrotron radiation in epitaxial thin films of magnesium niobate. It is shown on the basis of obtained results that polar nano-regions in relaxor films is governed by mechanisms other than soft mode condensation.

## Molecular dynamic simulation of damage formation in GaN under atomic and molecular ion bombardment

Published in category «Condensed matter physics»

Results of atomistic simulation of (0001) GaN surface bombardment by 50 eV/a.m.u. atomic (F, P, Ag) and molecular (PF[2] and PF[4]) ions are presented. Strong in-cascade recombination of generated point defects is found. Final defect distributionsare significantly shifted towards the surface. Both these findings are in good agreement with experimental data on formation of structural defects in GaN under accelerated ion irradiation. Enhanced defect generation as compared to approximationgiven by binary collisions is found for heavy atomic (Ag) and molecular (PF[4]) ions. In the case of molecular ion the mentioned effect is observed close to the sample surface only.

## The influence of collision cascade density on GaN surface topography and surface shift under atomic and molecular ion bombardment

Published in category «Condensed matter physics»

Effect of collision cascade density on GaN surface properties under molecular and atomic ion bombardment have been studied. At low level of cascade density swelling prevails sputtering. In the case of molecular ion irradiation, when cascade is high, sputtering is more effective than swelling. Threshold behavior of these phenomena is established and corresponding values are found. Physical reasons are suggested.

## Mathematical modeling of solid particles motion in submersible separators

Published in category «Simulation of physical processes»

Mathematical model of solid particles tracking in submersible gravity and hydrocyclone separators has been put forward. Optimal geometry parameters of the devices were chosen. The calculated and experimental data were compared.

## Energy spectrum and optical transitions in CdHgTe nanoheterostructures

Published in category «Atom physics and physics of clusters and nanostructures»

Experimental results of photoluminescence in CdHgTe nanoheterostructures are presented. Calculations of size-quantization levels in CdHgTe with quantum wells were performed with account for the effect of nonparabolicity of the energy-versus-wave vector dependence. Our experiments confirmed possibility of observation optical transitions involving electrons and light holes in the quantum-well structures.

## A comparison of macroscopic and microscopic methods of calculation of dielectric permittivity of dense ultracold atomic clouds

Published in category «Atom physics and physics of clusters and nanostructures»

In this article we discuss the problems of theoretical description of light interaction with complex atomic systems, chilled down to very low temperatures. Basic actual approaches are outlined and the results are compared.

## The excited states of argon-xenon molecules in the far ultraviolet area studied using the (3+1) REMPI method

Published in category «Atom physics and physics of clusters and nanostructures»

The photoionization spectra of ArXe dimer molecules near the excited states Xe* 7p, 6d in the high-energy area 87500 - 90000 cm^(-1) close to the energy of ionization of molecules were recorded by the method of three-photon excitation of molecules followed by one-photon ionization, (3+1) REMPI method. There are 12 states of Xe* in this area, two of these states are allowed at three-photon excitation. The spectrum recorded by monitoring the molecular ions ArXe+ hasthe complicated image. The dissociation limits of two vibrational systems were measured: ArXe*→Ar1S0+Хе*7р[5/2]2 andAr1S0+Хе*6d[7/2]03. For these excited states the molecular constants and the potential curves were calculated. These data were obtained for the first time.

## Terahertz nanoantenna based on carbon nanotubes modified chemically with boron or nitrogen

Published in category «Atom physics and physics of clusters and nanostructures»

The effects of chemical modification of the carbon nanotubes (CNTs) due to injection of the boron or nitrogen atoms on the electromagnetic properties of CNTs are studied. The calculation of the band structure of carbon nanotubes modified chemically is performed using the linear augmented cylindrical wave method. Semiclassical model for the dynamics of electrons is used to calculate the linear conductance of CNTs. To investigate the antenna characteristics of CNT a scattering of plane electromagnetic wave on CNT is considered and a boundary problem for Maxwell’s equations is analyzed. It is demonstrated that the substitution of carbon atoms for boron or nitrogen is an effective way to improve antenna characteristics of CNTs.

## The fluorescent microscope upgrading to investigate biological structures with subdiffractional resolution

Published in category «Experimental technique and devices»

An upright fluorescence microscope, which is a part of the Optical Tweezers set-up, is upgraded to perform localization microscopy. The resolution of 50 nm was obtained with a test object. Recommendations on upgrading already existing or newly bought microscopes to perform localization microscopy and on calibrating and testing upgraded microscopesare proposed.

## Electrodes of single-phase alternating current plasma torches and materials for its production

Published in category «Experimental technique and devices»

The paper deals with problems which solution is necessary to provide maximal lifetime of electrodes for alternating current plasma torches. Investigation of erosion resistance of various materials intended for electrode production is represented in the paper. The experimental data obtained in the course of the long-time lifetime testing of the plasma torches are reported.

## The influence of constructional features of Si(Li) detector on the amplitude spectrum form

Published in category «Experimental technique and devices»

The paper considers some aspects of the influence of the detector constructional features on the shape of the amplitude spectrum of Si(Li) detector as an example. The results of the detector imitation program and of the incomplete charge collection from dead layers are described.

## Energy characteristics of a charged particle in a plane monochromatic wave and in a magnetostatic field

Published in category «Physical electronics»

The problem of a charged particle motion in an external field of a plane electromagnetic wave and a uniform magnetostatic field has been analyzed. The motion of particles with different initial conditions was considered. The dependence of particle energy on the intensity of electromagnetic wave and the frequency ratio was obtained.

## The measurement of attenuation in polymer optical fibers doped with fluorescent dye

Published in category «Physical optics»

The new method of measurement of attenuation in dye-doped polymer optical fiber based on side illumination is put forward. Attenuation coefficient of different polymer optical fiber doped with Rhodamine 6G dye is measured. The influence of conditions of measurements on measuring attenuation coefficient is detected.

## The measurement of main characteristics of light hadrons in gold nuclei collisions at 39.0 and 62.4 GeV

Published in category «Nuclear physics»

√s=_{[NN]}39.0 and 62.4 GeV have been presented. Comparison of nuclear modification factors measured for π0-mesons in Cu+Cu and Au+Au collisions at √s_{[NN]}= 22.4, 39.0, 62.4 and 200 GeV was carried out. It is shown that maximum energy of SPS synchrotron at CERN is not enough to reveal the jet-quenching effect.

## The theorem on existence of a bounded solution of the Cauchy problem for the Frankl system of hyperbolic type

Published in category «Mathematics»

The conditions of resolvability of the Cauchy problem have been obtained for a hyperbolic system of first order quasilinear partial differential equations. The investigation of the characteristic properties of the solutions was based on the method of an additional argument.

## The calculation of the subgraph with the maximal pseudo-density

Published in category «Mathematics»

In this paper a new approach to effective calculation of a subgraph with the maximal density has been found. A pseudo-density is defined as the |E|/|V| ratio of the G = (V, E) graph. The use for solving consecutive scheduling problem is considered.

## Splitting expansions for the ordinary quasi-linear differential equations in the limiting problems

Published in category «Mathematics»

The splitting procedure transforms a quasi-linear limiting problem into a sequence of linear limit problems. The split sequence equations form Hamilton’s systems connected to the conditions of the extremum.

## An antiplane problem for a crack penetrating into an elastic inclusion provided the phase contact is imperfect

Published in category «Mechanics»

In the paper we consider an interaction of the semi-infinite crack of mode III with circular elastic inclusion. Imperfect contact at the interface is supposed. The interface conditions are described by a spring-type model assuming that the traction continuity remains intact, while the displacement experiences a jump proportional to the interfacial traction. As a result the use of the generalized integral transform of Mellin the problem reduced to hypersingular integral equation. Exact analytical solution in closed form of this equation is founded. For the stress intensity factor the simple mathematical formula is obtained. Two limiting situations are studied: the case of perfect contact and the caseof sliding contact.

## The rotational speed determination for a bush in the floating ring bearing with allowance of lubrication hydrodynamics and centrifugal forces

Published in category «Mechanics»

Our study gives the theoretical representation of the rotational speed determination for the bush in the floating ring bearing with allowance of lubrication hydrodynamics and centrifugal force. The basic results are referred to the short bearing investigation.

## Equilibrium states of integrated Newtonian fluid

Published in category «Mechanics»

General form of viscous tension tensor for integrated Newtonian fluid in the high-frequency vibration field has beenobtained in this work. Conditions of equilibrium and quasi-equilibrium states of integrated Newtonian fluid in the free shape closed cavity were formulated. Besides solid state existence condition for Bingham liquid was described.

## The proof of effect of shielding of a harmonious wave of vertical polarization by an isotropic plasma layer

Published in category «Radiophysics»

The elementary proof of effect of shielding of a harmonious wave of vertical polarization by an isotropic plasma layer with a maximum electronic concentration is obtained as losses in a layer tend to zero if a frequency of a wave is equal to the maximum plasma frequency of a layer.