A new free energy equation is deduced; it serves as a basis for the derivation of an equation for the homogeneous phase of a hard-sphere system. It exactly reproduces all the known virial coefficients and agrees with the molecular dynamics data within their accuracy. The absence of singular points during transition from the stable region to the metastable region is shown. According to the properties of the statistical integral, the free energy and the equation of state have a singularity at close packing.
Show AbstractWe study the connection between quasi-classical field theory and axiomatic statements of the quantum field theory, Schwinger source theory, and the Lehmann-Symanzik-Zimmermann (LSZ) formalism. The classical Schwinger source is connected with the classical field; the LSZ $R$-function is connected with the quantum field operator. The axioms of the quantum field theory are written in the context of the quasi-classical expansion. In the considered approach, the stationary action principle and canonical commutation relations for field operators are obtained as corollaries and are not postulated as initial statements of the theory.
Show AbstractA comparative study of the results of the simulations of the photodisintegration of heavy nuclei in the energy range corresponding to the giant dipole resonance by the TALYS software package and by a combined model of is carried out. The cross sections of photoabsorption, photoneutron, and photoproton reactions and of the excitation of isomeric states for Hg and $^{208}$Pb isotopes are calculated. The results of the calculations are compared with the known experimental data.
Show AbstractThe problem of determining the average value and dispersion of the process during the noninertial detection of a random stationary process, with the feedback taken into account, using a Schottky diode with $\delta$-doping is investigated. The dependence of the output parameters on the input ones has been obtained in the Gaussian approximation.
Show AbstractWe study the impact of the type of the pulse sequence, the registration algorithm, and the data processing regime on the shape of a two-dimensional heteronuclear $J$-spectrum. It is shown that the widely used processing techniques for two-dimensional heteronuclear $J$-spectra can lead to a distortion of lineshapes and a significant loss of information. We suggest a scheme of optimal transformation of the free induction decay signal that allows one to obtain a phase-sensitive spectrum with cross-peaks that have absorption lineshapes in both frequency coordinates. The result was tested experimentally on chloroform-$^{13}$C, a model spin system of the AX type.
Show AbstractIt is shown that the inverse Faraday effect appears in the case of surface plasmon polariton propagation near a metal/paramagnetic interface. The inverse Faraday effect in nanostructured periodically perforated metal-dielectric films increases because of the excitation of surface plasmon polaritons. In this case, a stationary magnetic field is amplified by more than an order of magnitude compared to the case of a smooth paramagnetic film. The distribution of an electromagnetic field is sensitive to the wavelength and the angle of incidence, which allows one to effectively control the local magnetization that arises due to the inverse Faraday effect.
Show AbstractFormulas for the limit vacuum and Pears currents of a thin hollow relativistic electron beam propagating in a cylindrical drift chamber of the coaxial cross section are derived.
Show AbstractThe results of investigation of the IR spectra of optical density under the condition of attenuated total internal reflection of acetonitrile in porous glasses with the pores of different radii are presented. It is established that interaction between the acetonitrile molecules and the porous glass matrix with the pores of small dimensions (1.3–4 nm) significantly effects the spectral characteristics of these molecules.
Show AbstractThe results of a study of charge transfer luminescence (CTL) in a YAG:Yb monocrystal and trans-parent ceramics obtained by vacuum sintering and nanocrystalline (VSN) technology from a weakly agglomerated powder are presented. The kinetics of CTL decay at temperatures of 8, 100, and 300 K and different excitations were obtained. The results of the measurements are analyzed from the viewpoint of comparison of monocrystal and ceramics properties. The high quality of the latter is demonstrated.
Show AbstractThe resonance behavior of electric and magnetic dipole moment amplitudes that are induced in metallic nanoparticles by the scattering of incident light was obtained by numerical simulation. For a split-ring resonator a full set of polarizability matrix components, including magnetoelectric coupling parameters (bianisotropy), were calculated.
Show AbstractIn some crystals, polymers, and gels that contain hydrogen bonds OH…O, NH…O of length 2.8–3 Å or water molecules, gigantic anomaly of dielectric permittivity (ɛ ∼ 10$^3$–10$^6$) is observed in certain circumstances at frequencies of 1–10$^6$ Hz, which is accompanied by peculiarities in conductivity σ and dielectric losses tanδ. In crystals this effect appears after a sudden cooling to −50°C and it is observed at slow heating in the range of 20–40°C. At the return temperature course from 40°C dependences ɛ(T), σ(T), and tanδ(T) have their usual values. Anomalies in objects that differ by their compositions are unified by their temperatures, which are all close to 40°C. Authors have made an attempt to explain the similarity of these phenomena by the features of hydrogen bonds that are present in the objects.
Show AbstractThe structural transformations and magnetic phase transitions in the quasibinary system Y(Fe$_{1-x}$Al$_x$)$_2$ have been investigated by Mössbauer spectroscopy, X-ray diffractometry, and magnetic measurements of polycrystals.
Show AbstractThe problem of the model description of the electron state at the deep impurity level in a semiconductor is solved. The potential of the impurity center is chosen as the superposition of a Coulomb field and a spherical quantum well with a flat bottom. The energy level and the wave function of the ground state are determined by the exact method and the variational Ritz method in wide ranges of parameters of the well. An algorithm for determining the energies and wave functions of the first excited states is presented. The advantages of the variational method over the exact solution are demonstrated.
Show AbstractThere are no established methods that have a sensitivity during the determination of an adsorbed polymer film mass that is not worse than 1 ng that do not require additional calibration and the usage of reference measures. A highly sensitive method for measuring an adsorbed polymer is proposed in this work. The added mass was determined by the change of the resonance frequency of a cantilever used in atomic-force microscopy (AFM) as a probe. A modification of the cantilever surface is proposed that allows one to avoid the affect of the adsorbed polymer on the cantilever force constant. The mass of poly(diallyldimethylammonium) (PDDA) chloride adsorbed on the cantilever surface was obtained with a sensitivity of 0.01 ng using an AFM cantilever.
Show AbstractTo determine the variations in the secondary structure of α-chymotrypsin related to changes of function, we measure the ATR-FTIR spectra of the lyophilized enzyme, its solutions in normal and heavy water, tablets wetted in acetonitrile and cyclohexane, and suspensions in these solvents. The experimental results show that the most significant structural changes (a decrease in the content of α-helical fragments and an increase in the content of β-sheets) are related to the transition from the aqueous solution to the lyophilized sample. Similar but less developed structural changes are observed for the transition from the lyophilized sample to suspensions in organic solvents.
Show AbstractIn the context of the problem of energy transport in solar flares, simplified analytical models have been developed that describe plasma heating in the solar atmosphere by heat fluxes from the super-hot (${T_e \geq 10^8}$ K) reconnecting current layer. It is shown that the applicability conditions of common heat conduction produced by Coulomb collisions of electrons in plasma are not fulfilled in solar flares. The heat flux calculated using the classical Fourier’s law proves to be significantly higher than the real energy fluxes known from modern multi-wavelength observations of flares. The so called anomalous flux produced by interaction of free electrons with ion acoustic waves in a plasma is critically analyzed. The question of what the dominant mechanism of heat transfer in solar flares is requires additional consideration [1].
Show AbstractThe physical properties of the process of heat transfer from a solar-flare’s energy source (a high-temperature reconnecting current layer) to the surrounding plasma of the Sun’s atmosphere are investigated. Major attention is given to consideration of the collisional relaxation of the heat flux and to analysis of its related effects. The physical meaning of this phenomenon is that the heat flux responds to a change in the spatial temperature distribution with a delay rather than immediately, as in the simplest approximation described by the classical Fourier’s law. It is shown that this mechanism describes the heat transfer in flares better than classical and anomalous heat conduction (see Part 1).
Show AbstractIt is shown that the gas surrounding a hot star is excited mainly by the stellar radiation field. The contribution of the excited states to the ionization rate $R_{\rm exc}$ can noticeably exceed that of the basic state $R_{\rm base}$. A simple approximation formula is obtained for the ratio $R_{\rm exc}/R_{\rm base}$.
Show AbstractThe amplitude, phase, and period of free liberation and the amplitudes of five fundamental harmonics of forced (annual, semi-annual, …) librations of Mercury in longitude are determined based on the analytical theory of Mercury’s liberation (on an elliptical orbit) in longitude using a high-accuracy complex method for ground-based radar tracking.
Show AbstractThe relationships between the energy of small-scale turbulence and its dissipation rate are studied based on the data of long-term high-frequency measurements of temperature and wind velocity fluctuations in urban area. It is shown that the energy of wind velocity turbulent fluctuations is linearly related to the dissipation rate ɛ. The proportionality coefficient between turbulent kinetic energy (TKE) and ɛ is dimensional and does not depend on the stratification of the atmosphere, the Richardson number, or the Monin-Obukhov scale. Measurements in different seasons show that this coefficient can be related to the mean velocity of adiabatic motions (sound speed or air temperature), which enables one to select a more universal constant, γ. A linear relationship between the temperature fluctuations variance (the characteristic of the inner energy of turbulence) and their dissipation rate is also shown. The revealed proportionality is confirmed by measurements in urban and forest conditions, as well as in the surface layer over a flat desert terrain.
Show AbstractAn additional pole term and the contributions to it from intermediate states with the same mass but with different spins is calculated for the Compton scattering amplitude on a two-particle system with zero total angular momentum. It is shown that the decomposition of invariant amplitudes on the generalized polarizabilities of the system does not take place if this term is taken into account.
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