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Nguyen-Truong H.T.,Volgograd State Technical University
Journal of Electron Spectroscopy and Related Phenomena | Year: 2014

An approach to include plasmon damping in the energy-loss function is described within the dielectric theory. Use of the energy-loss function included damping for calculating the electron inelastic mean free path yields results in good agreement with the experimental data and other theoretical results at medium-high energies. At a few eV above the Fermi energy, the present results are entirely consistent with those obtained from other measurements for Au. Also, a simple way to predict the values of damping and lifetime at low energies is described. Two values of lifetime for an electron with energy (above the Fermi energy) of 5 eV in Al and 6 eV in Au are predicted to be 2.18 fs and 1.70 fs, respectively. These predicted values are in reasonable agreement with those estimated from other measurements at the corresponding energies: 2.16 ± 0.22 fs in Al, and 1.91 ± 0.32 fs in Au. © 2014 Elsevier B.V.


Kryuchkov S.V.,Volgograd State Technical University | Kukhar' E.I.,Volgograd State University
Physica E: Low-Dimensional Systems and Nanostructures | Year: 2012

In tight binding approximation the explicit view of electron energy in graphene superlattice was derived. The possibility of propagation of the cnoidal waves in graphene superlattice is discussed. The direct current induced perpendicularly to the superlattice axis by cnoidal and sinusoidal electromagnetic waves under the presence of longitudinal constant electric field was calculated. Such direct current was shown to change its direction when the intensity of longitudinal electric field changes its absolute value. © 2012 Elsevier B.V.


The maximum energy loss for electron stopping power calculations by the full Penn algorithm within the dielectric formalism is determined with taking into account the contribution of electron and plasmon excitations. Use of these calculated electron stopping powers in Monte Carlo simulations applying continuous slowing down approximation gives the backscattering electron yields in much better agreement with experimental data than previous other theoretical results. The muffin-tin model is used to describe the electron elastic scattering by atom bound in solids with taking into account the exchange correlation and polarization effect. © 2013 AIP Publishing LLC.


Nguyen-Truong H.T.,Volgograd State Technical University
Journal of Physical Chemistry C | Year: 2015

We present an approach for introducing damping into the Penn algorithm by using the Mermin dielectric function instead of the Lindhard dielectric function. We find that for a damping of 1.5 eV, the electron inelastic mean free path calculated by the present algorithm for Al is in excellent agreement with experimental values in the energy range 5-9 eV. Meanwhile, for a damping of 2.0 eV, our result for Au is consistent with the GW+T ab initio calculation at several electronvolts. In particular, at an energy of 1 eV, our result for Au is 297 Å and lies within the range 220-330 Å obtained from measurements by ballistic electron emission microscopy. © 2015 American Chemical Society.


Nguyen-Truong H.T.,Volgograd State Technical University
Ultramicroscopy | Year: 2015

We propose a modified Bethe formula for low-energy electron stopping power without fitting parameters for a wide range of elements and compounds. This formula maintains the generality of the Bethe formula and gives reasonable agreement in comparing the predicted stopping powers for 15 elements and 6 compounds with the experimental data and those calculated within dielectric theory including the exchange effect. Use of the stopping power obtained from this formula for hydrogen silsesquioxane in Monte Carlo simulation gives the energy deposition distribution in consistent with the experimental data. © 2014 Elsevier B.V.


Zauer E.A.,Volgograd State Technical University
Chemistry of Heterocyclic Compounds | Year: 2011

The enthalpy of formation in the gas phase has been calculated for 21 carbonyl compounds of the thiophene series with the aid of the PM3, MINDO, AM1, and MNDO semiempirical quantum-chemical methods. Comparison of them with experimental data showed that the best linear correlation was achieved with the PM3 method. The latter in conjunction with a developed linear regression equation has been used to predict the enthalpy of formation of 22 carboxylic acids and ketones of the thiophene series. © 2011 Springer Science+Business Media, Inc.


Kryuchkov S.V.,Volgograd State Technical University | Kukhar' E.I.,Volgograd State University
Physica B: Condensed Matter | Year: 2013

d'Alembert equation written for the electromagnetic waves propagating in the graphene superlattice is analyzed. The possibility of the propagation of the solitary electromagnetic waves in the graphene superlattice is discussed. The amplitude and the width of the electromagnetic pulse are calculated. The drag current induced by such wave across the superlattice axis is investigated. The numerical estimate of the charge dragged by the solitary wave is made. © 2012 Elsevier B.V. All rights reserved.


Lysak V.I.,Volgograd State Technical University | Kuzmin S.V.,Volgograd State Technical University
Journal of Materials Processing Technology | Year: 2015

The determination of the energy balance in explosive welding is an important scientific task because information on the itemized expenditure of the energy given off during an explosion makes it possible to manage energy release items and, consequently, to effectively control the structure and properties of the composite materials produced. In the general case, the energy liberated during an explosion is used for the interaction of welded plates: it is spent on the acceleration of the flyer plate and is also wasted on the dispersion of explosion products. A calorimetric method was used to determine the portion of the energy transferred to the flyer plate by detonation products. It was determined that the amount of energy does not exceed 1% of the total energy of the explosion. It was also shown that during the collision of explosively welded plates, a portion of the kinetic energy of the flyer plate transforms into other types of energy and is also released as heat; this energy was measured using the calorimetric method. The heat is given off in the weld joint area as a result of the shock wave action, which crushes the microrelief of the welded surfaces, plastically deforms the metal in the collision area (shear and wave formation) and leads to dissipative losses throughout the metal body of the welded plates. A method is proposed to determine energy losses occurring in the system of colliding plates. This method is based on laminated models and makes it possible to determine a quantitative relation between energy losses on the jet, on the one hand, and the kinematic parameters of explosive welding, on the other. The contribution of explosive welding parameters to the amount of energy spent on the plastic deformation of metal in the collision zone is analysed. The results obtained make it possible to evaluate the explosive welding efficiency required for explosive welding: the efficiency is determined by the specific energy of an explosive converted to the energy spent on the plastic deformation of metal in the weld joint zone. It is shown that the efficiency varies from 0.5 to 3%, depending on the welding regime. © 2015 Elsevier B.V. All rights reserved.


Kryuchkov S.V.,Volgograd State Technical University | Kukhar' E.I.,Volgograd State University
Superlattices and Microstructures | Year: 2014

The electron spectrum of graphene superlattice is shown to be modified under the high-frequency electric field. Using this modified electron spectrum d'Alembert equation is written for the electromagnetic waves propagating in the graphene superlattice. Under certain conditions the d'Alembert equation is shown to take the form of double sine-Gordon equation. The solutions corresponding to the solitary electromagnetic waves are obtained. The shapes of these waves are shown to depend on the amplitude of the high-frequency electric field. © 2014 Elsevier Ltd. All rights reserved.


Lysak V.I.,Volgograd State Technical University | Kuzmin S.V.,Volgograd State Technical University
Journal of Materials Processing Technology | Year: 2012

Like in any solid state method of metal bonding, a weldability area exists for each pair of explosion welded materials. Establishing the lower boundary of explosive welding is a relevant task because it makes it possible to specify the parameters of the explosive welding process. The existing concepts and models of the lower boundary are comprehensively reviewed, and the evolution of ideas on the subject is described. The axis "average mass of the explosion welded plates" is added to the original representation of the welding areas in the "hydrodynamic" coordinates "collision angle-collision velocity". Such an approach makes it possible to analyse the bonding process in terms of energy. A new parameter - the pressure deforming pulse - is proposed. This parameter depends on the collision conditions and relates the pressure in the contact area to the time period within which the pressure operates. Thus, it presents the explosive welding lower boundary in the physical coordinates "pressure-time-temperature". © 2011 Elsevier B.V. All rights reserved.

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