Table of contents

The seventeenth Russian Youth Conference on Physics and Astronomy (PhysicA.SPb) was held from 28-30 October 2014 in Saint Petersburg, Russia. The Conference continues the tradition of Saint Petersburg Seminars on Physics and Astronomy originating from the mid-1990s. Since then PhysicA.SPb maintains both the scientific and educational quality of contributions delivered to the young audience. This is the main feature of the Conference that makes it possible to combine the whole spectrum of modern Physics and Astronomy within one event.

PhysicA.SPb/2014 has brought together more than 200 students, young scientists and their professor colleagues from many universities and research institutes across the whole of Russia as well as from Belarus, Ukraine, Finland, the Netherlands, France and Germany. Oral and poster presentations were combined into the well-defined sections of Astronomy and Astrophysics, Optics and spectroscopy, Physics of ferroics, Nanostructured and thin-film materials, Mathematical physics and numerical methods, Biophysics, Plasma physics, hydro- and aero-dynamics, and Physics of quantum structures.

This volume of Journal of Physics: Conference Series presents the extended contributions from participants of PhysicA.SPb/2014 that were peer-reviewed by expert referees through processes administered by the Presiders of the Organising and Programme Committees to the best professional and scientific standards.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

First optical observations of γ-ray pulsars J2055+2539, J2043+5740, J1957+5033 have been obtained with the BTA 6m optical telescope. We found no reliable counterpart candidates to these pulsars. However, upper limits on optical fluxes were derived. Comparison of PSR J2055+2539 and PSR J2043+2740 optical limits and their X-ray spectral data likely suggests the presence of spectral breaks between the optical and X-rays in the multiwavelength emission of these pulsars. X-ray spectral data for PSR J1957+5033 are not yet available. In spite of rather deep Hα-observations of PSR J2055+2539, a bow shock nebula, which was expected for the pulsar, has not been detected. Probably, the density of the interstellar medium surrounding the pulsar is not enough for a bright Hα bow shock to be formed. We also find the further deeper observations of pulsars J2055+2539 and J2043+5740 are reasonable, while a large gamma-ray position error ellipse for J1957+5033 is crowded by background sources and its coordinates should be updated using X-ray observations before any further optical study.

Studying thermal evolution of neutron stars (NSs) is one of a few ways to investigate the properties of superdense matter in their cores. We study the cooling of isolated NSs (INSs) and deep crustal heating of transiently accreting NSs in X-ray transients (XRTs, binary systems with low-mass companions). Currently, nearly 50 of such NSs are observed, and one can apply statistical methods to analyze the whole dataset. We propose a method for such analysis based on thermal evolution theory for individual stars and on averaging the results over NS mass distributions. We calculate the distributions of INSs and accreting NSs (ANSs) in XRTs over cooling and heating diagrams respectively. Comparing theoretical and observational distributions one can infer information on physical properties of superdense matter and on mass distributions of INSs and ANSs.

We discuss here the Flicker-Noise Spectroscopy approach to studying astrophysical systems, for example the radio wave intensity of quasi-stellar object (QSO) 1641+399 and BL Lacertae (BL Lac) 0215+015 in different frequency ranges. The presented method allows to parameterize the study dynamics using a short set of characteristics. The considering sources have a significant differences in manifesting the non-stationary effects, dynamical intermittency and synchronization. The radio wave intensity dynamics of the BL Lac 0215+015 is characterized by well-defined set of natural frequencies, persistent behavior with low effects of non-stationarity and high level of frequency-phase synchronization. For dynamics of the QSO 1641+399 reverse occurs including the asymmetrical structure of cross-correlator. Our findings show that using the flicker-noise spectroscopy approach to studying astrophysical objects allows to carry out the more detail analysis of their behavior and evolution.

We present the 2D axisymmetric model of particle acceleration at colliding shocks from supernova remnant and stellar wind from the nearby star. The model is the expansion of the previously developed plane-parallel model and takes into account three three-dimensional structure of the stellar wind and the supernova remnant shock. Numerical and analytical calculations provides the energetic and spatial distributions of the particles accelerated by colliding shock flows system. The presented model can be used in calculations of the emission spectra of different stellar associations and star clusters with colliding shock flows.

We present a new analysis of the quasar spectrum J 2123-0050 obtained using VLT/UVES. The H2/HD absorption system at z = 2.059 was analysed. This system consists of two subsystems with z_A = 2.05933 and z_B = 2.05955. The HD lines have been detected only in subsystem A with the column density of log N = 13.87 ± 0.06. We have determined the column density of H₂ in this subsystem, log N = 17.93 ± 0.01, which is about three times larger than estimation derived early from analyses of quasar spectrum obtained using KECK/HIRES [1]. The derived ratio HD/2H₂ = (4.28 ± 0.60) × 10^-5 is the largest in quasar spectra, nevertheless it coincides with the primordial deuterium abundance within 2σ error. Additionally, we have found some evidence in the partial covering effect for the H₂ system.

The abundance of cosmogenic isotopes in natural samples is the main source of information about past variations of cosmic ray intensity, in the solar activity and in the strength of the geomagnetic field. Sharp increases could originate from powerful impulsive events such as solar flares, gamma-rays from supernova explosions and gamma-ray bursts. A significant increase in the radiocarbon record has been detected recently in tree rings around AD 775 [1]. Both large solar proton event (SPE) [2] and gamma-ray burst (GRB) in our Galaxy [3] are favored as a source. However, either of the explanations faces difficulties of low event rate because of detection of a similar peak around AD993 [4], [5]. What is more, we know other similar result [6]. We carried out a statistical analysis of these three data sets. It is shown that AD 775 event differs fundamentally from AD 993 and AD 1006 events, because the last two can be explained without the assumption of the impulsive event.

The interaction of primary cosmic rays with the Earth's atmosphere is investigated using the simulation toolkit GEANT4. Two reference lists of physical processes - QGSP_BIC_HP and FTFP_BERT_HP - are used in the simulations of cosmic ray cascade in the atmosphere. The cosmic ray neutron fluxes are calculated for mean level of solar activity, high geomagnetic latitudes and sea level. The calculated fluxes are compared with the published results of other analogous simulations and with experimental data.

We derive an analytic approximation for the emissivity of neutrino-pair bremsstrahlung (NPB) due to scattering of electrons by atomic nuclei in a neutron star (NS) crust of any realistic composition. The emissivity is expressed through generalized Coulomb logarithm by introducing an effective potential of electron-nucleus scattering. In addition, we study the conditions at which NPB in the crust is affected by strong magnetic fields and outline the main effects of the fields on neutrino emission in NSs. The results can be used for modelling of many phenomena in NSs, such as cooling of young isolated NSs, thermal relaxation of accreting NSs with overheated crust in soft X-ray transients and evolution of magnetars.

We try to establish the correlation between different parameters of "butterfly-diagrams" derived from the analysis of solar observational data for the 12-23 solar activity cycles and the values in the models of α-Ω­dynamo using RGO - NASA/Marshall data set. We have ascertained that there is a linear relationship between S and BT/L for all the investigated cycles, where S is the mean area of the sunspots (umbrae), B is the mean magnetic field strength, T is duration of a cycle and L is the mean latitude of the sunspots in a cycle.

The relativistic pulsar winds are forming the pulsar wind nebulae (PWN) — the unique extended sources of non-thermal radiation detected in all bands of the electromagnetic spectrum. High angular resolution imaging of the PWN with modern orbital and ground-based telescopes makes possible to study the highly non-equilibrium processes in the pulsar wind plasma. Physical interpretation of the observed dynamic structures in the nebulae requires modeling of the relativistic pulsar wind. The main mechanism of emission of the magnetized relativistic pair plasma in the PWN is the synchrotron radiation, and the observed dynamical structures may be related with a propagation of perturbations of the magnetic field. A kinetic approach to highly non-equilibrium relativistic pair plasma allows us to evaluate the structure of the perturbation of the magnetic field propagating transverse to the mean quasi-stationary magnetic field. We present synchrotron images with the dynamic structures in the PWN simulated in the relativistic pair plasma with the strong scattering of pairs by the stochastic magnetic field fluctuation.

We analyzed first optical observations of 17 kyr-old PSR J2021+3651 and its pulsar wind nebula obtained with the 10.4-m Gran Telescopio Canarias (GTC) telescope in the Sloan r' band. In addition, we reanalyzed archival X-ray data obtained with Chandra. The pulsar and the nebula were not detected in the optical down to 27.20 and 24.85 magnitude 3σ limits, respectively. Using the optical and X-ray data we conclude that PSR J2021+3651, like the Vela pulsar, is a very inefficient nonthermal emitter in the optical and X-rays, while its gamma-ray efficiency is consistent with an average efficiency for all gamma-ray pulsars of similar ages.

The form of the outflows generated during the interaction of the accretion disc with the tilted stellar magnetosphere in the propeller regime is studied in the ballistic approach. The problem is solved analytically. Different ways of the flux expansion are considered. The results are applied to the description of the narrow absorption details observed in the spectra of young stars in a blue wing of the sodium D Na I resonance lines.

The linear relation between the temperature of the Cosmic Microwave Background and the cosmological redshift is a fundamental prediction of the standard hot Big Bang model. Measurements of the CMB temperature in the past can be done by means of observing radiative excitation of atomic and molecular species like C and CO. It can be detected in quasar spectra with z ∼ 2. We study excitation of CO rotational levels both by the CMB radiation and collisions. Corrections of determination of the CMB temperature due to collisional excitation by the analysis of CO molecule rotation level populations are proposed.

In this work, the selenocentric dynamic reference net was developed for the first time in the field of selendesy in order to address problems with space navigation. Three tasks were addressed in this research: a) the analysis of the mathematical model of the orthogonal coordinate transformation accuracy; b) the identification of the basic dynamic reference system objects with ones that are contained in reducing catalogues; and c) the extension of the base points net of the basic dynamic reference system. The result was a dynamic coordinate system summary that contains 1162 objects. The correlation analysis of this net was carried out and was found to coincide with modern dynamic coordinate systems that have been obtained. This selenocentric reference catalogue covers the full visible area of the Moon.

There is a new approach for the estimation of the position accuracy and proper motions of the stars in astrometric catalogues by comparison of the stars' positions in the researched and Hipparcos catalogues in different periods, but under a standard equinox. To verify this method was carried out the analysis of the star positions and proper motions UCAC2, PPM, ACRS, Tycho-2, ACT, TRC, FON and Tycho catalogues. As a result of this study was obtained that the accuracy of positions and proper motions of the stars in Tycho-2 and UCAC2 catalogues are approximately equal. The results of the comparison are represented graphically.

An influence of annihilation and decay of the dark matter particles on the baryon-to-photon ratio has been studied for different cosmological epochs. We consider the different parameter values of the dark matter particles such as mass, annihilation cross section, lifetime and so on. The obtained results are compared with the data which come from the Big Bang nucleosynthesis calculation and from the analysis of the anisotropy of the cosmic microwave background radiation. It has been shown that the modern value of the dark matter density Ω_CDM = 0.26 is enough to provide the variation of the baryon-to-photon ratio up to Δη/η ∼ 0.01÷1 for decay of the dark matter particles, but it also leads to an excess of the diffuse gamma ray background. We use the observational data on the diffuse gamma ray background in order to determine our constraints on the model of the dark matter particle decay and on the corresponding variation of the baryon-to-photon ratio: Δη/η ≲ 10^-5. It has been shown that the variation of the baryon-to-photon ratio caused by the annihilation of the dark matter particles is negligible during the cosmological epochs from Big Bang nucleosynthesis to the present epoch.

This work is devoted to exploring the influence of long-tailed synaptic weights distribution on neural population dynamics. We show numerically that both strong sparse and very weak connections pay crucial role for spontaneous activity whereas they almost do not influence on driven population activity. Moreover, according to obtained results, we suggest that neurons with strong connections form multiple chains, which are the core of spontaneous activity, whereas neurons with weak connections pay little role of partially enhancing of population activity.

A vibroacoustic fiber optic system that consists of micromechanical components designated for use in medicine and biology is reviewed. A theoretical analysis of a fiber optic microphone is done and its optimal construction parameters are determined. The possibility of using the developed system with magnetic resonance tomography to noninvasively measure man's arterial pressure is specified.

Thymine is the most sensitive DNA nucleobase to UV-irradiation. In the thymidine solution the photoreactions probability is in dependence on the solvent properties which determine stacking-mediated thymidine association and lifetime of excited states. In this work we investigated the degree of UV-irradiation induced thymidine damages in water, salt (NaCl) and ethanol solvents using UV absorption and circular dichroism (CD) spectrometry, and MS ESI method. In the explored systems thymidine association degree rose in the following solvent order: 1 M NaCl, water, ethanol. UV-absorbance and CD intensity fell in the greater extent in the ethanol and water-salt solutions than in water. So the experiment showed that the association degree of thymidine in the solution does not play a main role in its photosensitivity.

Interaction of native calf thymus DNA (ctDNA) with phenacylimidazo[5,1- a]isoquinoline derivatives was studied by the methods of spectrophotometry, viscometry, isothermal titration calorimetry (ITC) and dynamic birefringence. It was found that both of investigated compounds form complexes with the DNA molecule, the structure of compounds affects the mode of binding these ligands to DNA. The primary binding mode can not be described by the classical models of groove binding or intercalation. It has been suggested that the primary mode of binding is "partial intercalation".

In this work we apply a new method to determine the differences in characteristics of the cortical electroencephalographic (EEG) activity, measured during interictal stage (i.e., period between seizures), between healthy subjects and patients with epilepsy. To analyze the dynamical and spectral properties of bioelectric activity we use power spectra and phase portraits which are introduced on the basis of the Memory Function Formalism (MFF). We discover the significant differences in the types of power spectra of the EEG for healthy subjects and patients. We reveal the cerebral cortex areas for which the EEG activity of considered groups of subjects has a different structure of the phase portraits. The proposed approach can be used as an additional method for diagnosis of epilepsy during interictal stage.

In paper we apply the method based on the Flicker-Noise Spectroscopy (FNS) to determine the differences in frequency-phase synchronization of the cortical electroencephalographic (EEG) activities in patients with bipolar disorder (BD). We found that for healthy subjects the frequency-phase synchronization of EEGs from long-range electrodes was significantly better for BD patients. In BD patients a high synchronization of EEGs was observed only for short-range electrodes. Thus, the FNS is a simple graphical method for qualitative analysis can be applied to identify the synchronization effects in EEG activity and, probably, may be used for the diagnosis of this syndrome.

Low-temperature magnetic susceptibility of heavily doped Ge: As samples has been investigated by methods SQUID magnetometry and ESR spectroscopy near the metal-insulator phase transition. Paramagnetic component of the impurity magnetic susceptibility was investigated by ESR previously. Using both techniques make possible to determined the diamagnetic component of impurity susceptibility. The value of the impurity diamagnetic susceptibility equals to 5×10^-8 cm³/g and corresponds to the localization radius of the As donor- electron near the metal-insulator phase transition.

The problem of discrete spectrum for quantum graph with local disturbance of the periodicity is described. The Hamiltonian is determined as 1D Schrödinger operator on each edge and some boundary conditions at each vertex. The spectral analysis of the quantum graph having the form of branching strips with hexagonal (honeycomb) structure is considered in more details.

The layered system composed of metamaterial and vacuum layers is examined. We assume the metamaterial is the isotropic, homogeneous, dispersive and non-absorptive media. The permittivity and permeability of the metamaterial are equal and described by using a single Lorentz contribution. The electric Green's function is obtained for the case, when the permittivity and permeability of the metamaterial are equal -1. For this case we observe the no reflection effect. Also, the photonic band gap structure of the similar infinite layered system is described. For changing layers widths, the absence of the no reflection effect is shown.

High concentration of hydrogen in metal leads to hydrogen embrittlement. One of the methods to evaluate the hydrogen content is the method of thermal desorption spectroscopy (TDS). As the sample is heated under vacuumization, atomic hydrogen diffuses inside the bulk and is desorbed from the surface in the molecular form. The extraction curve (measured by a mass-spectrometric analyzer) is recorded. In experiments with monotonous external heating it is observed that background hydrogen fluxes from the extractor walls and fluxes from the sample cannot be reliably distinguished. Thus, the extraction curve is doubtful. Therefore, in this case experimenters use discrete TDS-spectrum: the sample is removed from the analytical part of the device for the specified time interval, and external temperature is then increased stepwise. The paper is devoted to the mathematical modelling and simulation of experimental studies. In the corresponding boundary-value problem with nonlinear dynamic boundary conditions physical- chemical processes in the bulk and on the surface are taken into account: heating of the sample, diffusion in the bulk, hydrogen capture by defects, penetration from the bulk to the surface and desorption. The model aimed to analyze the dynamics of hydrogen concentrations without preliminary artificial sample saturation. Numerical modelling allows to choose the point on the extraction curve that corresponds to the initial quantity of the surface hydrogen, to estimate the values of the activation energies of diffusion, desorption, parameters of reversible capture and hydride phase decomposition.

In the context of problems of hydrogen and thermonuclear power engineering intensive research of the hydrogen isotopes properties is being conducted. Mathematical models help to specify physical-chemical ideas about the interaction of hydrogen isotopes with structural materials, to estimate the limiting factors and to significantly reduce the expenses of experimental research by means of numerical simulation for different parameters and experimental conditions (including extreme ones). Classical diffusion models are often insufficient. The paper is devoted to the models and numerical solution of the boundary-value problems of hydrogen permeability taking into account nonlinear sorption-desorption dynamics on the surface. Algorithms based on difference approximations. The results of computer simulation of the hydrogen flux from a structural material sample are presented.

The possibility of creation of nanostructures on graphene and carbon nanotubes was investigated by placing different atoms at a single vacancy of graphene. Using the SIESTA software package and a high-throughput computing approach, we have consistently identified the binding energy and magnetic properties of 49 elements of the periodic table. The results show that all atomic species are stable at room temperature; some elements exhibit interesting magnetic behavior. E.g. Ni is not magnetic, whereas Al, Ga and P have magnetic moment. It is widely accepted that the rarity of metal-doped graphenes could be explained by the tendency of metal atoms to form clusters instead of doping. We analyzed corresponding binding energies and proved the opposite statement.

Charge accumulation and relaxation processes in the OFET active zone are studied. It is found that positive and negative charges injection from metal electrodes under drift field occurs. Characteristic time of these processes is found to be about 30 sec. Behaviour of charges under the combination of source-drain and gate potentials is also investigated.

Reproducible vacuum method of thin fullerene films production with Cd<Te> impurity on Si, glass and mica surfaces are developed. Thin composite films were obtained by Knudsen cell method. Initial studies of condensation and surface morphology of the films are investigated SEM methods. Optical spectroscopy was used to confirm the obtained results. Results showed the presence of an additional peak associated with the formation of C₆₀-CdTe molecular complexes. SEM results confirm absence of phase separation.

In this work we demonstrate the possibility of studying the current-voltage characteristics for single vertically standing semiconductor nanowires on standard AFM equipped by current measuring module in PeakForce Tapping mode. On the basis of research of eight different samples of p-doped GaAs nanowires grown on different GaAs substrates, peculiar electrical effects were revealed. It was found how covering of substrate surface by SiO_x layer increases the current, as well as phosphorous passivation of the grown nanowires. Elimination of the Schottky barrier between golden cap and the top parts of nanowires was observed. It was additionally studied that charge accumulation on the shell of single nanowires affects its resistivity and causes the hysteresis loops on I-V curves.

The paper presents brief research results of the admittance of metal-insulator- semiconductor (MIS) structures based on Hg_1-xCd_xTe grown by molecular-beam epitaxy (MBE) method including single HgCdTe/HgTe/HgCdTe quantum wells (QW) in the surface layer. The thickness of a quantum well was 5.6 nm, and the composition of barrier layers with the thickness of 35 nm was close to 0.65. Measurements were conducted in the range of temperatures from 8 to 200 K. It is shown that for structure with quantum well based on HgTe capacitance and conductance oscillations in the strong inversion are observed. Also it is assumed these oscillations are related with the recharging of quantum levels in HgTe.

Nearly monodisperse cadmium selenide quantum dots (QDs) were synthesized in non-coordinating solvent octadecene through phosphine-free method using oleic acid as surfactant. Selenium powder suspension in octadecene obtained by ultrasound processing was used as one of precursor solutions. Influence of multiple selenium precursor injections on nanocrystal growth process was investigated. Nanoparticles were characterized by means of absorption and photoluminescence spectroscopies.

We present the studies of self-assembled silver nanoislands on the surface of silver ion-exchanged glasses. The nanoislands were formed by out-diffusion of reduced silver atoms from the bulk of the glass to its surface. Control of silver ions distribution in the glass by thermal poling after the ion exchange allowed formation of relatively big, up to 250 nm, isolated silver nanoislands while without the poling an ensemble of silver nanoislands with average size from several to tens of nanometers with random size distribution was formed. The nanoislands were characterized using atomic force microscopy and spectral measurements. We used optical absorption spectroscopy for "random" nanoislands and dark field scattering spectroscopy for isolated ones, corresponding spectra showed peaks in the vicinity of 450 nm and 600 nm, respectively. The "random" nanoislands significantly enhanced Raman scattering from Rhodamine 6G, also the modification of Raman signal from deposited on the surface of the samples bacteriorhodopsin in purple membranes was registered.

The goal of our work was the investigation of the processes of interaction electrons (5-30 keV) with metal nanoparticles in glasses. The objects of our research were the silicate glasses containing Au and Ag nanoparticles. The experiments have shown that electron irradiation with electron energy 5-10 keV of glass containing Au nanoparticles results in the formation of high reflective gold film about 50 nm thick on a glass surface. Electron irradiation (5-30 keV) of glass containing Ag nanoparticles results in the increase of optical density in the irradiated areas and formation of silver clusters (Ag_x, x<5) in a form of a ring at periphery. Thus, electron beam can be used to produce photonic and plasmonic devices without etching mask.

A comparison of experimental electron backscattering diffraction patterns for porous Si formed by ion implantation and thermal annealing is presented. For this purposes Ag-ion implantation into monocrystalline c-Si substrates at energy of 30 keV with dose of 1.5×10¹⁷ ion/cm² was carried out. Surface nanoporous Si structures were studied by scanning electron microscope imaging and electron backscattering diffraction. Amorphization of Si after implantation and recrystallization of porous Si after annealing is observed. Ion implantation is suggested to be effective technique for a formation of nanoporous semiconductor layers, which could be easily combined with the crystalline substrate matrix for various applications.

The features of microstructure crystallization into perovskite phase in lead zirconate titanate film by femtosecond laser radiation of near-infrared range were discussed. In-situ crystallization kinetics by method of second harmonic generation (SHG) was studied. The presence of several types of crystallization was shown, including ultra-fast (explosive) crystallization occurring immediately after the start of exposure, and slow (self-sustaining) crystallization, occurring after termination of exposure. The advantage of the second-harmonic generation microscopy for the study of annealed microstructures was shown. The morphology of microstructures was investigated by transmission electron microscopy (TEM).

The UV LED GaN/AlGaN heterostructures obtained by HVPE approach were investigated. It was shown that the peak wavelength of UV LEDs was in the range of 360-380 nm with FWHM of 10-13 nm. At operating current of 20 mA, the active region temperature Tj was 43°C, the output optical power and efficiency - 1.14 mW and 1.46%, respectively. It was shown that the use of HVPE method allowed to achieve a high degree of structural perfection of epitaxial structures.

Electron paramagnetic resonance (EPR) was detected in the ground state of Ce³⁺ ions in YAG:Ce single crystals by monitoring the intensity of photoluminescence under nonresonant excitation. The photoluminescence intensity was found to increase strongly in magnetic field at liquid helium temperature. The optically detected magnetic resonance (ODMR) effect was of the order of percents and corresponded to resonance decrease in the luminescence intensity. ODMR correlated with the conventional EPR spectra of Ce³⁺ ions, which occupy the dodecahedral Y³⁺ sites in the YAG crystal lattice. The increase of the PL intensity in magnetic field was concluded to be caused by Boltzmann distribution between spin sublevels of the ground state of Ce³⁺ ions. The ODMR tend to equalize the populations of levels in resonance and results to a decrease of PL intensity. Different types of Ce³⁺ centres characterized by the presence of nearby antisite defects were observed, which should be taken into account in applications of single ion spectroscopy based applications of YAG:Ce.

Design, growth and studies of photosensitive structures based on Ag-GaP and Ag- Al_xGa_1-xN contacts are reported. Methods for structure selectivity control, which allow changing the sensitivity spectrum half-width in a range of 11-210 nm were worked out. By varying the metal layer thickness, a set of Ag-GaP short-wavelength photodetectors (PD) was fabricated. The set includes PDs from broadband (spectrum half-width Δλ=210 nm, sensitivity S_I = 0,19 A/W) to visible-blind (Δλ=15 nm, S_I = 0,034 A/W). The use of Ag-Al_xGa_1-xN structures provided increased sensitivity (S_I = 0,071 A/W) and Δλ reduced to 11 nm due to special selection of solid solution composition.

The novel technique for 3-dimensional (3D) spectral imaging is proposed. It is based on simultaneous spectral acousto-optic filtration of a pair of stereoscopic convergent light beams via single acoustic wave. A few promising configurations of such acousto-optic tunable filters (AOTFs) is proposed, discussed and compared. It is shown that these elements may be ultra-compact and PC controlled modules, ready to be integrated into many existing schemes of stereoscopic 3D imagers.The experiment carried out with the help of single-AOTF-based spectral stereomicroscope demonstrates the efficiency of proposed technique.

Random impedance networks with inductive L and capacitive C bonds have been widely addressed in a literature to describe properties of disordered metal-dielectric nanocomposites. In this paper we show that networks with single bonds in the form of parallel oscillatory LC-circuits and capacitances C are more appropriate model for metal-dielectric composite in optical frequency range. Resonant spectrum of such networks demonstrates absence of resonances at frequencies higher than the plasma frequency of metal ω_p. Eigenmodes of big ordered clusters are studied. Their resonances are shown to be surface modes having the form of multipoles of various order. It is in agreement with theory of surface plasmons in metallic nanowires. The idea for metal-metal and metal-semiconductor nanocomposites with different plasma frequencies is put forward.

The paper presents experimental observation of strain solitary waves in layered waveguides with layers made of two glassy polymers, PMMA and polystyrene. It is shown that in delaminated structures solitons propagate in each layer independently with parameters typical for waves in each material. In bars with layers bonded with the glassy adhesive a combined wave is formed, propagating as a single one in both layers and exhibiting soliton properties.

The paper presents a novel approach to detect and monitor nonradiative transitions in singlet oxygen molecules in water by means of holographic recording of thermal disturbances. The approach is realized experimentally using classical and digital holographic techniques. Advantages and disadvantages of each of the techniques are considered.

A significant number of papers investigate a propagation of intense two-color beam through air in conditions when inharmonic oscillations of valence electrons convert to a plasma nonlinearity. This paper extends the scope of analysis, examining more complex combinations of synchronized beams propagating through dielectric media: triple beam and a beam combined with quazi-static field. It is shown that adding a third harmonic to a mix of first and second ones does not show principal changes in interaction picture: all phenomena appear to be described well before. But adding a static field to an interaction scene shows new peculiarities in redistribution of pulse spectrum energy to infra-red wing of optical range.

We investigate the process of Casimir field indirect pliotodetection. The protocol of measurement is implemented via interaction between two-level atom and cavity. We evaluated basic statistical characteristics of conditional state of Casimir field.

An approach for compensating the influence of the interrogator noises on the readings of the extrinsic Fabry-Perot interferometric displacement sensor is proposed. With the use of a reference interferometer and special processing, the sensor resolution was about twofold improved and comprised 12-25 pm instead of 15-46 pm for a wide range of EFPI baselines.

A theoretical model of a microwave active ring filter based on a ferrite-ferroelectric layered structure serving as a waveguide for spin-electromagnetic waves is developed. An experimental prototype of the device is fabricated and characterized. The device is implemented as an active-ring resonator with a microwave amplifier and a ferrite-ferroelectric delay line. The resonance properties of this system are studied theoretically and experimentally. The results show dual control of central frequency of the filter with magnetic and electric fields. An effective Q-factor of 50 000 and tuning by 5 MHz with an electric field are achieved at 8 GHz.

Experimental results for narrowband filter based on yttrium iron garnet film epitaxially grown on gadolinium gallium garnet substrate have been shown. The principle of operation of the filter is based on excitation of Lamb modes in the substrate. We demonstrated also that the use of single crystal diamond as a substrate will significantly reduce the phase noise of the designed optoelectronic microwave generator.

The nonlinear phase shift and nonlinear damping of spin-electromagnetic waves were theoretically studied for the first time in sub-terahertz frequency range in infinite homogeneous longitudinal magnetized multiferroics. The research was based on the solution of the Ginzburg-Landau equation. It is shown that the saturation of the phase shift occurs due to the nonlinear damping if the nonlinear damping coefficients exceed v₁=10⁸ s^-1 and v₂=10⁹ s^-1.

We propose new non-optical mechanism of the pure spin current generation via Auger recombination in the quantum wells with Rashba spin-orbit coupling. It is shown that such process is allowed due to interference between the Coulomb matrix elements corresponding to two different transitions during Auger recombination, leading to non-diagonal transversal components of the spin current tensor, J_R = J^xy = −J^yx. In the limit of low temperatures the total spin current is proportional to the Rashba constant γ_R, spin relaxation time τ_s and the third power of both the concentration n, inverse quantum well width a^-1 and E_g^-2. Estimations show that typical magnitude of the generated spin current by this way is much greater than the ones obtained using intraband optical excitation mechanisms and comparable with spin currents driven by interband optical excitation, provided that the quantum well bandgap is narrow enough (E_g < 0.5 eV).

Optical properties of heterostructures with deep quantum wells have been studied in the framework of four-band Kane mode permitting a nonparabolic energy spectrum of charge carriers to be taken into account. The system AlSb/InAs_0.84Sb_0.16/AlSb was used as an example. It is established that the nonparabolicity weakly influences the overlap integral between s- and p-states, but notably increase the state density and optical absorption coefficient in the conduction band.

Method of manufacturing substrates for self-catalyst/free-catalyst ordered growth of the nanowires has been developed. Experiments show the possibility of autocatalytic growth of ordered GaAs NWs on the substrates produced during the research.

The numerical model of a plasma asymmetric dipole antenna is studied in this paper. This antenna consists of a dielectric tube with discharge plasma and a metal screen. The plasma in the tube is simulated by Particle-in-cell (PIC) method. The spectra of the electromagnetic field components were studied in the plasma and the near antenna field for various antenna operating modes. The operating modes depend on a ratio of a plasma frequency and a frequency of radiated electromagnetic wave. Langmuir frequency component was found in spectra within plasma for all antenna operating modes. The amplitude of this spectral component is greater than the amplitude of the component at the carrier frequency for nonradiative and non-linear modes. The biggest amplitude of the radiated signal spectrum is at the carrier frequency in the linear mode.

Numerical simulation of a two-temperature three-component Xenon plasma flow is presented. A solver based on the OpenFOAM CFD software package is developed. The heat flux at the shock tube end wall is calculated and compared with experimental data. It is shown that the heat flux due to electrons can be as high as 14% of the total heat flux.

We show that harmonic vibrations in amorphous silicon can be decomposed to transverse and longitudinal components in all frequency range even in the absence of the well defined wave vector q. For this purpose we define the transverse component of the eigenvector with given ω as a component, which does not change the volumes of Voronoi cells around atoms. The longitudinal component is the remaining orthogonal component. We have found the longitudinal and transverse components of the vibrational density of states for numerical model of amorphous silicon. The vibrations are mostly transverse below 7 THz and above 15 THz. In the frequency interval in between the vibrations have a longitudinal nature. Just this sudden transformation of vibrations at 7 THz from almost transverse to almost longitudinal ones explains the prominent peak in the diffusivity of the amorphous silicon just above 7 THz.

Hybrid spin-electromagnetic wave (SEW) envelope solitons have been studied both experimentally and theoretically. The solitons were formed during auto-generation of SEWs in an active ring resonator for which the role of the nonlinear dispersive waveguide media was played by a multiferroic layered ferrite-ferroelectric structure. It is demonstrated that the dielectric constant of the structure affects the nonlinear properties of SEWs.

The paper reports on development of tunable band-pass microwave filters for microwave photonic generators. The filters were fabricated with the use of epitaxial yttrium iron garnet films. Principle of operation of the filters was based on excitation, propagation, and reception of spin waves. In order to obtain narrow pass band, the filtering properties of excitation and reception antennas were exploited. The filters demonstrated insertion losses of 2-3 dB, bandwidth of 25-35 MHz, and tuning range of up to 1.5 GHz in the range 3-7 GHz.

We have experimentally studied a chaotic dynamics of bright spin-wave soliton trains. Thin yttrium iron garnet films having pinned surface spins were used for the experiments providing propagation of highly dispersive dipole-exchange spin waves. Chaotic soliton trains were excited in the frequency band around low-frequency part of dipole gap of spin wave spectrum. Analysis of fractal dimension, embedding dimension, and Lyapunov exponents was carried out based on measured time profiles of chaotic soliton sequences. We find that the fractal dimension and Lyapunov exponents are weak function of carrier frequency around dipole gap whereas embedding dimension is almost constant.

Design of a UV sensor based on an yttrium-iron garnet/diamond layered cavity is presented. The operation principle of the sensor is based on the change in the spin-wave dispersion law and, consequently, in the frequency and Q-factor of eigenmodes of the cavity under study upon appearance of free carriers generated by UV light.

A phase noise of the microwave oscillators based on spin-wave delay lines is theoretically investigated. Theoretical results show that spin-wave damping in the delay line limits a phase reduction with increasing time delay. It is possible to find an optimum value of the time delay for each particular value of damping decrement in order to provide minimum phase noise of the generated microwave signal.

A phase noise of microwave oscillators having an active ring circuitry with a spin- wave delay line is theoretically and experimentally investigated. The delay line was made with yttrium iron garnet (YIG) film epitaxially grown on gadolinium gallium garnet substrate. Obtained results demonstrate a management of the oscillator phase noise with a variation of the distance between antennas used for excitation and reception of spin waves in the YIG film.

Propagation of spin waves in a one-dimensional magnonic crystal to a finite distance have been studied theoretically. It was shown that, in contrast to the ideal spatially unlimited magnonic crystals with zero loss, there are no band gaps in the real magnonic crystals. The effective spectrum of spin waves at frequencies close to the Bragg resonances strongly depends on the magnonic crystal length.

Properties of spin-electromagnetic wave chaos developed in active ring oscillators have been investigated. A multiferroic structure composed of yttrium iron garnet film and barium strontium titanate (BST) slab served as a nonlinear dispersive medium of the oscillator. Dual control of the fractal dimension of the chaotic signal attractor was realized by variation of the ring gain and dielectric permittivity of the BST slab.

Development of a microwave dynamical chaos in an active ring oscillator based on a ferromagnetic film upon a gradual increase of the ring gain has been studied. It was demonstrated that the transition of the system from steady-state to chaotic dynamics is in good agreement with the Ruelle-Takens scenario. The attractors of the dynamic system were reconstructed from the experimentally measured waveforms, and a numerical analysis of their parameters was made.

Physical basis of using the controlled defect formation in InGaAs heteroepitaxial layers to vary the carrier lifetime is considered. It is shown that the lifetime of nonequilibrium carriers in the base layers of a diode can be controllably varied from several to hundreds of nanoseconds. The results obtained in a study of (i) structural defects and their rearrangement related to the lattice mismatch between the heteroepitaxial InGaAs layer and the GaAs substrate and (ii) influence exerted by these defects on the carrier lifetime and on the voltage blocked by diode structures are reported. Dynamic switching characteristics of high-speed power heteroepitaxial diodes at different temperatures are presented.

The three-dimensional (3D) indicatory surfaces of thermal expansion in crystals of different categories were constructed in program MathCad. Indicatory surface of thermal expansion is a sphere, spheroid, ellipsoid or surface of multiple parts, depending on the category of the crystal symmetry. The symmetry elements of thermal expansion include the symmetry elements of the point group of the crystal according Neumann's Principle.