Spatial macroscopic structure of a pulsed microsecond discharge in barrier-metal gaps with a nonuniform electric field distribution

Electric and spatial characteristics of a pulse-periodic microsecond barrier discharge are investigated in different geometries—triangular prism, plate, and corrugated electrode—that are in contact with a dielectric plate and form a dihedral angle with it. It is established that, in the space of the dihedral angle, the regions of discharge represent alternating cylindrical layers with the axes lying on the contact line. The first conducting layer is formed at some distance from the contact edge of the electrode. The number of layers and their localization are determined by the angle formed between an electrode and the dielectric plate. A physical model explaining the main features of the structure formation is proposed.     

Specific features of the strain-induced order-disorder phase transition and its mechanisms

In the present paper, the methods of x-ray diffractometry are used to investigate the influence of plastic deformation on the long-range atomic order in alloys with L1₂, L1₂(M), and L1₂(MM) superlattices. The influence of ordering energy, initial values of the long-range order parameter, and average sizes of antiphase domains on the specific features of the dependence of long-range order parameter on the strain degree is considered. It is demonstrated that the wetted strain-induced order-disorder phase transition occurs with rapid accumulation of antiphase boundaries that play an important role in the destruction of long-range atomic order.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 21–32, September, 2004.     

Electron Metal-Dielectric Phase Transitions in Semiconductors under Pressure

The effect of uniform pressure on the character of metal-dielectric transitions in compensated weakly- and highly doped semiconductors (WHDCS) is considered. The influence of hybridization of resonance quasilocalized impurity states with band continuum states on the transition is shown. Minimum metallic conductivities in p-CdSnAs₂ are determined for Mott and Anderson transitions. Special features of the metal-dielectric transformation in weakly-doped narrow- and high energy-gap semiconductors are discussed for the case of hydrogen-like impurities. Anderson localization in WHDCS is also considered. Phase diagrams are presented.     

Effective equation of nonlinear pulse evolution in a randomly anisotropic medium

Propagation of a light pulse through a weakly inhomogeneous optical fiber is analyzed. The non-linear envelope equation describing the evolution of polarized pulses is determined by statistical properties of inhomogeneities in the optical fiber. The isotropic Manakov system of equations is shown to be applicable in the presence of high-frequency small-scale defects in the fiber. In the presence of only large-scale inhomogeneities, the signal dynamics are described by an anisotropic system of equations.     

Isotopic effect in the width of a giant dipole resonance in light nuclei

An isotopic effect in the widths of giant dipole resonances is established on the basis of an analysis of the latest systematics of photoabsorption cross sections for nuclei containing 12 to 65 nucleons. This effect arises owing to isospin splitting of a giant resonance and is enhanced by its configuration splitting.     

Photoanisotropic compositions with an extended spectral range of anisotropy

Experimental data for two-and three-component compositions (dyes embedded in gelatinous and polymeric matrices) that are Weigert-sensitive to polarized radiation in a wide spectral range are reported. It is shown that the matrix considerably affects the photoanisotropic properties of the compositions.     

Clusterization of Stochastically Wandering Particles in Potential Fields

Computer models belonging to the class of models of growth controlled by a gradient are investigated. A theoretical approach to the construction of model algorithms of this class allows us to obtain a wide variety of clusters with different structures, including fractal ones. A consideration of gradient increments to the potential leads to the formation of vertical, nonbranching, and insulated clusters corresponding to a long-range potential with large gradient.     

Vibrations of excited molecules at combination and difference frequencies

In the context of the theory of molecular vibrations, by applying the direct product operation of matrices, an equation for the vibrations of vibrationally excited molecules at combination and difference frequencies is obtained. From the solution of this equation, elements of vibration patterns and expressions that can be used for the study of changes in the molecular structural parameters and the coefficients of kinematic interactions are determined. The formulas obtained are applied to the calculation of the anharmonic electro-optical parameters of the molecules of water H₂O and its two isotopes H₂ ¹⁷O and H₂ ¹⁸O. These calculations are performed in terms of the semiempirical quantum-chemical CNDO/2 method and by numerical differentiation of dipole moment functions by employing a cubic spline approximation.     

Mathematical Simulation of the Synthesis of cis-1,4-Polybutadiene on a Cobalt-Containing Catalyst in the Presence of Ethylene

Based on an analysis of experimental results and published data, the main elementary steps of the anionic coordination polymerization of butadiene rubber on a cobalt-containing catalyst in the presence of ethylene were found, and a mathematical model of the periodic process at an optimum water content was developed. The molecular-weight characteristics of the process depending on ethylene concentration were studied with the use of this model.