Inconsistency in the application of the adiabatic theorem

The adiabatic theorem states that an initial eigenstate of a slowly varying Hamiltonian remains close to an instantaneous eigenstate of the Hamiltonian at a later time. We show that a perfunctory application of this statement is problematic if the change in eigenstate is significant, regardless of how closely the evolution satisfies the requirements of the adiabatic theorem. We also introduce an example of a two-level system with an exactly solvable evolution to demonstrate the inapplicability of the adiabatic approximation for a particular slowly varying Hamiltonian.     

Model of delocalized atoms in the physics of the vitreous state

A development of the model of delocalized atoms of liquids and glasses is proposed. It is shown that the basic equation of the model for the probability of delocalization (excitation) of an atom can be obtained not only from the Clausius relation but also by other methods of statistical physics. Techniques for calculating the parameters of the model are developed. The critical displacement of an atom from the equilibrium position, which corresponds to the maximum interatomic attraction force, can be considered as a delocalization (local excitation) of this atom in an elastic continuum. The energy of the critical displacement of an atom calculated as the work of the limit elastic deformation of the interatomic bond in an elastic continuum is in agreement with the results of calculation by the model of delocalized atoms. This energy can also be calculated from the data on surface tension and atomic volume. In silicate glasses, the process of delocalization of an atom represents the critical displacement of a bridging oxygen atom in the structural fragment of a silicon-oxygen (Si-O-Si) network before the switching of the valence bond, whereas, in amorphous organic polymers, the delocalization of an atom corresponds to the limit displacement of a fragment of the main chain of a macromolecule (a group of atoms in the connecting link).     

Determination of the Luminescent Impurity Concentration in Solution in the Presence of Intense Background Luminescence

A method of excitation-emission matrix (EEM) processing is proposed for determining the concentration of polyaromatic hydrocarbons in aqueous media in the presence of an unknown intense background signal exceeding the legitimate signal by a factor of 15–20. The theoretical substantiation and experimental test of the efficiency of the proposed method have been performed with the use an aqueous solution of anthracene as an example.     

Estimation of the parameters of charge carriers in polymers in the vicinity of the threshold of thermally stimulated switching

The temperature dependences of the parameters of charge carriers in thin films of an electroactive poly(diphenylenephthalide) polymer are investigated in the range preceding the thermally stimulated electronic switching (110–400 K). The thermally stimulated current spectra and current-voltage characteristics are measured in the same temperature range. The parameters of charge carriers are estimated in the framework of the model of injection currents limited by the space charge. It is revealed that the charge carrier mobility decreases with an increase in the temperature in the range from 110 to 400 K. A correlation between the temperature behavior of the current-voltage characteristics and the thermally stimulated current spectra is established. The possible contribution of the Pool-Frenkel effect is considered, and the inference is made that the electric field plays an important role in the thermally stimulated electronic switching.     

Temperature-induced changes in the EPR spectrum of the magnetic center in kaolin

Studies of kaolin have revealed an effect characterized by an unusual temperature-induced change of the EPR spectrum of the Fe3+ ion, which is the magnetic probe in kaolin-clay. At low temperature (T=4.2 K) a resonance line with an effective g-value g1=4.13 +/- 0.16 is observed. At high temperature (T=288 K) one observes a resonance line with the effective g-value g2=2.15 +/- 0.1. The transition from the low- to high-temperature spectrum is gradual and it is accompanied by a redistribution of the absorption intensity. The observed properties of the temperature dependence of the EPR spectrum are characteristic of systems with a multiminimum potential.     

Employment of the scattering amplitude in solving the diffraction problems for waves in a halfspace

The problem on the diffraction of an acoustic wave by a finite-size scatterer (inclusion) located in a halfspace is considered. The method of solving this problem is based on the use of the scattering amplitude of the inclusion. A formula analogous to the Green formula is presented. It allows one to determine the scattering amplitude of the inclusion for an arbitrary incident wave (determined by the directional pattern of the source of primary waves) from the scattering amplitude corresponding to plane incident waves. The algorithm is presented for solving the problem on the operation of an acoustically opaque radiator in a halfspace whose boundary is characterized by an arbitrary reflection coefficient. As an example, the problem is solved on the generation of low-frequency oscillations by a sphere with an acoustically soft boundary near an acoustically hard or soft boundary of the halfspace.     

Increase in the accuracy of approximating the profile of the erosion zone in planar magnetrons

It has been shown that the use of the survival function of the Weibull distribution shifted along the ordinate axis allows one to increase the accuracy of the approximation of the normalized profile of an erosion zone in the area from the axis to the maximum sputtering region compared with the previously suggested distribution function of the extremum values. The survival function of the Weibull distribution is used in the area from the maximum to the outer boundary of an erosion zone. The major advantage of using the new approximation is observed for magnetrons with a large central nonsputtered spot and for magnetrons with substantial sputtering in the paraxial zone.

     

Analytical Solution of the Problem of the Electrovortex Flow in the Hemisphere with Finite Size Electrodes in the Stokes Approximation

An analytical solution was obtained for a stationary axisymmetric motion equation for a flow caused by an inhomogeneous electric current propagating through an electrically conducting liquid. The problem was solved in the variables for vorticity and velocity vector potential in hemispherical geometry with the finite size electrodes. Stokes and electrodynamic approximations were used.     

Evaluating the performance of Russia in the research in nanotechnology

Many toxicology studies on insoluble and poorly soluble nanoparticles point out surface area as an indicator of inhalation exposure. Measuring this criterion thus constitutes an important challenge. Instruments exist which can measure particle surface area concentration in real-time, but it is not known how well they perform when faced with polydisperse nanostructured aerosols. In this study, the response functions of three commercially available instruments based on diffusion charging (LQ1-DC, Matter Engineering; NSAM, TSI model 3550; AeroTrak? 9000, TSI) were measured for monodisperse aerosols of four different chemical natures with particles ranging in size from 15 to 520?nm. Our results show good agreement between the experimental and theoretical response functions for the three instruments studied. In addition, no significant effect of the chemical nature, density or particle morphology was revealed. Instrument response was also tested with polydisperse aerosols. For these aerosols, discrepancies were observed between measurements and calculated concentrations based on response function and particle number size distribution. Relative differences varied between ?60 and +55?% with an average value of ?20?%. These differences may be explained by different factors; among them, the existence of a distribution of electrical charges on particles can lead to identical signals measured, and differential diffusion charging performance might lead to concentration-dependent response.     

Primary vertex in the ALICE experiment in absence of the event reconstruction

ALICE is a general-purpose apparatus for the study of ultra-relativistic heavy-ion collisions at the Large Hadron Collider of the CERN. The study of such reactions demands the determination of the primary vertex in three dimensions with good resolution. We have developed an algorithm for finding the vertex position even in absence of the event reconstruction. The performances of such an algorithm have been studied as a function of the vertex position, particle multiplicity and magnetic field.     

Three-body problem in the theory of the dielectric constant

We study the corrections to the Clausius-Mossotti formula for the dielectric constant of a disordered system of polarizable spherical particles. Previously we have derived an exact cluster expansion for the correction terms. Here we study the three-body correction in detail. We derive an explicit expression for the integrand of the three-body cluster integral for a system of polarizable point dipoles.     

Analysis of the adjustment precision of the stretcher in the petawatt laser facility

Effects of stretcher adjustment aberration on the residual dispersions of the laser system is analyzed making use of the ray tracing method. It is shown that the adjustment aberrations affect the pulse contrast and we must select an appropriate adjustment precision for the stretcher in the petawatt laser system. And as an example, a proper adjustment precision of the pulse stretcher is also proposed for the SHENGUANG (SG) II laser facility.     

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用KMR模型研究了等离子体中多光子非线性Compton散射下电子相轨道的演化,发现电子与光子进行能量交换后,只有未被俘获电子的相轨道才能从周期性向非周期性、随机型演化,其演化剧烈程度随电子吸收光子数的增大而加剧,随电子与光子碰撞非弹性成分和碰撞前初始速度的增大而迅速减弱,但低于强激光场中的剧烈程度。当电子被光场俘获时,这种演化过程结束并做稳定的运动,光子不再为电子提供能量。     

Compton散射下等离子体中电子相轨道的演化

用KMR模型研究了等离子体中多光子非线性Compton散射下电子相轨道的演化,发现电子与光子进行能量交换后,只有未被俘获电子的相轨道才能从周期性向非周期性、随机型演化,其演化剧烈程度随电子吸收光子数的增大而加剧,随电子与光子碰撞非弹性成分和碰撞前初始速度的增大而迅速减弱,但低于强激光场中的剧烈程度。当电子被光场俘获时,这种演化过程结束并做稳定的运动,光子不再为电子提供能量。     

On the possibility of wake-field effects in the conductivity of doped semiconductors

The formation of a wake field around a swift ion passing through an electron gas and the resulting contribution to the stopping power acting on the ion is an intensively studied phenomenon in metals and semiconductors. The present investigation serves to clarify whether an analogous effect, namely the formation of wake fields and a corresponding contribution to the resistivity, might occur in the Galilei-transformed case of electronic transport in doped semiconductors where the gas of drifting charge carriers passes through an array of fixed impurity ions. By use of an appropriate dynamical screening theory we show that indeed a local plateau in the current density versus field characteristic has to be expected whenever the mean drift energy per carrier exceeds the sum of the mean thermal carrier energy and the zero-point energy of the longitudinal plasma mode of the carrier gas. However, our survey of the published literature suggests that this condition might be too stringent, at least for bulk materials and standard experimental situations, where the strong carrier heating in the high-field regime of relevance in combination with other drift-limiting mechanisms or interband electron-hole avalanching would always precede and prevent the formation of the wake.Dedicated to Prof. H.-J. Queisser on the occasion of his 60th birthday     

Low-temperature conductance of the weak junction in InAs nanowire in the field of AFM scanning gate

We have investigated the conductance of an InAs nanowire in the presence of an electrical potential created by an AFM scanning gate at liquid helium temperature. The influence of the direction of a local electrical field on the tunneling rate through a weak junction in the InAs wire is clearly observed. To explain this behavior, the redistribution of the electrons among conductive channels in the wire must be taken into account. We have confirmed that the pattern of Coulomb blockade diamonds gives the same result for the ratio of quantum dot sizes as that revealed by scanning gate imaging.     

Equilibrium Plasma Configurations in the Vicinity of the Generic Point

The structure of an arbitrary equilibrium plasma configuration in an external potential field and a potential force magnetic field are studied in the plane geometry.     

On the elimination of the t-explicit divergence in the calculation of transport coefficients

Through an analysis of the expression of the autocorrelation function of the velocities in the matrix representation, an identification is made of all the matrix elements which lead to the so-called t or ? explicit divergence. The terms in the expansion can be easily summed and as a result the divergence is eliminated. A comparison with the procedure recently developed by Bartis and Oppenheim is made.     

Areal objects and the problem of the λ term in the theory of gravitation

The following areal objects are considered: an ether thread contracting two material points and a multidimensional ether fibre in the pseudo-Euclidean world of events. An ether space-time model with an arbitrarily determined Riemannian metric is constructed and the problem of the λ term in Einstein equations is discussed in this regard.     

Rearrangement of the horizontal space-time structure of the sound field in shallow water in the presence of moving internal waves

The rearrangement of the space-time structure of the sound field in a shallow-water waveguide with a moving intense internal wave packet is considered. The analysis is performed in terms of an approach characterized by space-time horizontal rays and vertical modes. It is shown that, within the time the packet travels over the acoustic track (about an hour), considerable spatial and temporal fluctuations occur in the field intensity and interference structure.