A model of the Coulomb multiple dissociation (Coulomb explosion) of a nanocluster that glides at an atomic distance along an organic film at a velocity that is lower than the Bohr velocity is proposed. Nanoclusters that consist of identical atoms and films, whose molecules contain substructures of periodic diatomic valence bonds, (for example, С$_n$Н$_2n$) that have a significant dipole moment are considered. These structures can serve as antennas for IR radiation. It is shown that the dissociation process of a gliding nanocluster is induced by a picosecond pulse of highly intense photons (1014–1016 W/cm$^2$) that are radiated by IR antennas of the film as a result of the relaxation of collective vibrating excitations that are accumulated in the antenna (excimoles). These excimoles resonantly exit from the IR antennas of the film as a result of the action of the periodic Coulomb field, which appears during the gliding of a nanocluster with respect to the film molecules at a rate below the Bohr velocity. In the framework of the proposed model, the experimental results on the decay of $C_{60}^+$ ions as they glide along an organic film that contains molecules with IR antennas are analyzed.
Show AbstractAn algorithm for reconstructing the decision rule that is used for classifying scene images under the theoretically-possible problem definition is generated and illustrated by means of a computing experiment. The algorithm can be used in geophysics for analyzing the shape of acoustic signals [1], for interpreting satellite imagery [2], etc.
Show AbstractThe energy spectrum of a nonrelativistic quantum particle in the confinement state in a closed spatial volume at general boundary confinement conditions (the Robin conditions) is investigated. It is shown that the properties of such a state are substantially more nontrivial compared with particle confinement using the potential barrier. It is also shown for a hydrogen-like atom arranged in a spherical cavity with radius R that if the surface layer with nonzero depth d plays the role of the boundary of the confinement region, all the energy levels of a discrete spectrum of the atom have a finite limit at R→0, while the R-dependence of the lower layer at physically substantial parameters of the surface layer contains a deep well-pronounced minimum, in which the binding energy is considerably higher than for the lower 1s level of a free atom.
Show AbstractThe purpose of this paper is to study the asymptotic properties of time autocorrelation functions for the generalized nonlinear Boltzmann-Enskog model, which contains a long-range component of the interaction between the particles. On the basis of the analysis of non-linear features of the Boltzmann-Enskog kinetic equation, the role of nonlinear effects is directly revealed at the approach to an equilibrium state. It is shown that autocorrelation functions have power asymptotics $t^{-3/2}$, and the effects that are related to the inclusion of the long-range component lead to a change in the coefficient at $t^{-3/2}$. These results establish a closed expression for the determination of coefficients in the asymptotic expansion of the autocorrelation functions of rate and thermal diffusion.
Show AbstractPhotofission of $^{238}U$ by bremsstrahlung photons is studied at four energies of the electron accelerator: 19.5, 29.1, 48.3, and 67.7 MeV. The yields of the fission fragments after the emission of prompt neutrons are obtained using the gamma - ray spectroscopic technique. The mass distributions of photofission are obtained at different upper energies of the bremsstrahlung spectrum. The ratio of the symmetric fission mode to the asymmetric is obtained from the mass distribution. The symmetric mode is shown to become 3-4 times greater than the asymmetric, as the excitation energy of the $^{238}U$ nucleus increases from 12 to 16 MeV
Show AbstractA system for the automatic acquisition and analysis of gamma-ray spectra that is used in the studies of photonuclear reactions with the activation technique in described. The system is comprised of a database, which is used to access data over a network, and of a spectrum analysis program. Experimental procedures and data analysis are greatly simplified with the use of the described system.
Show AbstractAn urgent task in the field of sensitized solar cells (DSSC) is to decrease the temperature of thermal annealing of titanium dioxide photoanode. In this work, we use a titania based polymer as organic “polylinker,” which allows low temperature annealing. This polylinker, which is obtained by means of partial hydrolysis of titanium polybutyltitanate or tianium 2-methoxyethoxide allowed us to decrease the annealing temperature of titanium dioxide down to 150–180°C. This permits the manufacture of DSSC on flexible polymer substrates. DSSC samples with efficiency of energy conversion up to 1% are obtained.
Show AbstractAn ab initio DFT study of atomic and electronic structure of carbyne crystals was carried out. The influence of hydrogen impurities on carbyne structure was investigated. Calculations with atomic relaxations showed that carbon chains in the carbyne crystal structure are bow-like curved; free-energy calculations showed that the most probable lengths of those chains are four and six atoms, which is in a good agreement with experiments. Carbyne-crystal electronic-structure analysis showed that there is a small gap of 0.09 eV near the Fermi level in four-atomic carbyne, while there is no such gap in six-atomic carbyne. In studying of the hydrogen impurity influence on the atomic and electronic structure of carbyne crystals, hydrogen atoms were embedded in two directions: across and along carbon chains in the crystal. As a result we found that the crystal structure is not distorted in the case of hydrogen embedded across the chains, while the type of bonding between carbon atoms in carbon chains in the carbyne crystal structure depended on the impurity concentration. The crystal structure was distorted when hydrogen was embedded along the chains. The concentration of impurities influences the conductivity of a carbyne crystal.
Show AbstractSome general laws of the dispersion behavior of electric characteristics are considered for various dielectric materials. The mechanisms of relaxation processes and linear dielectric response in the ɛ″(ɛ′) diagram are discussed.
Show AbstractThe average binding energy and the level width for the resonant D$^{(-)}$-state in a quantum molecule have been calculated in the presence of an external electric field. The calculations were performed in the zeroradius potential model with allowance for the tunneling decay of the resonant state. The external electric field is shown to stimulate the decay of resonant D$^{(-)}$-states under conditions of dissipative tunneling. It was found that the curve of the probability of photoionization of the D$^{(-)}$-center as a function of the external electric field strength has two peaks that are connected with a change in the symmetry of the double-well oscillator potential of the quantum molecule and with the transformation (caused by the electric field) of envelope wave functions, respectively.
Show AbstractSamples of nitrogen-doped nanocrystalline titanium dioxide were studied by electron-paramagnetic resonance technique. It was found that the doping of a material with an admixture of nitrogen leads to the appearance of nitrogen-containing paramagnetic centers, viz., N⊙ and NO⊙ radicals. The recharge effect of these centers was observed during illumination. These results may be useful for the development of photocatalytic filters based on doped nanocrystalline titanium dioxide.
Show AbstractThe atomic and electronic structures of AgAuAg, AuAgAg, and AuCoCo mixed nanocontacts are investigated by the method of first-principle molecular dynamics. The characteristic interatomic distances in contacts depending on their component composition are determined. The interrelationship between the structural and electronic properties of mixed nanocontacts is shown. The formation of stable bonds between the atoms of various elements in the contact chain, which makes it possible to explain the cause of stabilization and an increase in the contact strength at large interatomic distances is found. It is shown that the addition of Co atoms into pure-gold nanocontacts increases their strength (increases the breaking force of the contact), while the addition of Ag atoms leads to an increase in the range of interatomic distances at which the existence of the nanocontact is possible.
Show AbstractMechanisms of the formation of additional capacity of sorbent in sorption experiments of nitric acid and the separation of acid and salt in solution are studied using mathematical modeling. A method for the calculation of the dielectric constant and the ratio of concentrations of molecules and electrolyte ions in the inner layer of the sorbent is proposed. A mathematical model is constructed, simulation results are presented, and their comparison with experimental data is performed.
Show AbstractThe energy dependence of a thimble-chamber calibration coefficient is modeled in this work according to beam quality using the Monte Carlo method. The maximums of the deviations were observed within the range of photon energies that correspond to the giant dipole resonance for light elements. The deviations may reach 10% at photon energies of up to 25 MeV.
Show AbstractThe problem of the motion of a star in a close binary system with a conservative mass exchange is considered. In contrast to the well-known Paczynski-Huang model, a new model is used that defines the motion of close binary systems in the case of an elliptical orbit. The reactive forces and the force of gravity of stars by the overflowing jet are accounted for in the elliptic motion of the star. The calculations of elliptical orbits of close binary stars show that the effect of the reactive force on the evolution of the star orbit can be different. The changes of the major axis and eccentricity of the orbit of the second star are defined. The results are applied to the BF Aurigae star system and are given in the form of figures.
Show AbstractAn axially symmetric equilibrium model of Jupiter’s magnetodisk is developed in the MHD approximation that takes the plasma corotation and the centrifugal force into account. The model is constructed for two cases: (1) the magnetodisk plasma is assumed to have a uniform temperature; (2) the plasma pressure is assumed to be an adiabatic function of density. Analytical expressions for the magnetic field, current density, and magnetodisk temperature and thickness distributions are obtained as functions of the system parameters, viz., the radial distribution of plasma pressure in the equatorial plane, the transverse magnetic field in the center of the layer, and the angular velocity of the plasma rotation.
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