Improvement of accuracy of interferometric measurement of wedge angle of plates

A method is proposed for improving the accuracy of measuring the wedge angle of transparent plates using a lateral-shear holographic interferometer. Consecutive processing of a pair of interferograms with doubled number of interference fringes leads to reduction of the observational error by a factor of two compared to traditional interferometric methods. Data on the experimental validation of the method are presented.     

Simulation of the superlinearity of dose characteristics of thermoluminescence of anion-defective aluminum oxide

The specific features revealed in the superlinearity of dose dependences of thermoluminescence of anion-defective aluminum oxide single crystals have been considered theoretically in terms of the model of an interactive trap system. The model explains the decrease in the degree of superlinearity at a low heating rate, as well as with an increase in the dose increment, the occupancy of deep traps, and the sensitivity of the crystals to radiation due to the increase in the concentration of luminescence centers. The obtained results indicate a widening of the possibilities of the model for interpreting experimental data in the investigation of the dose characteristics of thermoluminescence of the studied crystals.     

Measurement of degree of polarization of fluorescence of pure anthracene crystalline film

The polarization ratio (I _b/I_a) of fluorescence of a monocrystalline film of pure anthracene is measured correcting for all probable errors. Comparison with decay-time data brings out that deviation from the value obtained from absorption measurements is due to a loss of intensity in the a-polarized fluorescence as compared to what is expected from absorption data. This is interpreted as an evidence that anthracene crystal fluorescence is emitted from regions of local lattice imperfections. It is confirmed that the first electronic transition takes place along the short axis of the anthracene molecule.     

Formation of One-Dimensional Distributions of Values of Correlators of Network Traffic Aggregates

Russian Physics Journal - A mathematical model of the flow of aggregated load characteristics of network traffic data packets in the form of a set of analytical signals is proposed. The real parts...     

Distribution of zeros of the partition function of the lattice gases of fisher and of temperley

The distributions of zeros of the partition function of lattice gas models of Fisher (at some temperature) and of Temperley are obtained. The former is a closed loop crossing the real axis and the latter is a part of the negative real axis.     

Calculation of energy characteristics of adsorption of metals

Within the framework of the electron density functional, a technique is developed for calculation of the adsorption energy and variation in the electron work function for metal substrates due to metal atom adsorption. The corrections to the local density approximation, which are associated with non-uniformity of the electron density in the subsurface region and discontinuous ion charge distribution over the crystal lattice sites, are included into consideration. It is shown that adsorption of alkali metal atoms results in lower electron work function, while that of transition metals (cobalt, iron, and chromium) might both decrease and increase the electron work function. Formation of a variety of adsorption structures from metal atoms depending on the temperature is discussed. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 7, pp. 14–19, July, 2007.     

Rectangularity of hysteresis loop of ferrites as a function of volume of reverse domains in state of remanence

A study is made of the dependence of the coefficient of rectangularity of the hysteresis loop of ferrites of the Li-Mn-Mg and Mg-Mn-Zn system on the volume concentration of residual reverse domains. The latter is calculated from the results of measurements of the relative remanence on the basis of a model developed. It is shown that a high degree of loop rectangularity can be attained not only in the absence of reverse domains but also in the presence of a considerable volume concentration of such domains.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 109–114, June, 1978.     

Analysis of spectral characteristics of scattering of evanescent waves

The spectral scattering characteristics of nanoscale particles exhibited in the field of evanescent waves are analyzed using the method of discrete sources. The effect of various parameters on the behavior of the scattering characteristics is studied. The material of the particles is shown to have the most substantial effect on the scattering cross section.     

Generation of superpositions of coherent states of the motion of a trapped ion

We propose a method for preparing superpositions of coherent states of the motion of an ion in an anisotropic two-dimensional trap, in which the ion is tightly bound in the y direction. In the scheme the ion is excited by two resonant laser beams with equal amplitude, propagating along the x and y directions, respectively. In the Dicke-Lamb limit, an initial coherent state of the ion motion can be converted into a superposition of several coherent states on a circle through the laser-ion interactions and state-selective measurements on the ion. Received: 30 May 1997 / Revised: 29 July 1997 / Accepted: 22 October 1997     

Amenability of discrete subgroups of the group of diffeomorphisms of the circle

The amenability of several discrete subgroups of the group of diffeomorphisms of the circle is proved.     

Role of interactions of triplets of atoms in the formation of elastic properties of cubic crystals

It is widely known that the interaction of triplets of particles (which are not reducible to the sum of pair interactions) play an important role in formation the nonlinear and anisotropic properties of crystals. The aim of this work is to establish a general form of the dependence of these properties on interactions of triplets of atoms that is dependent only on the structure of the crystals. To separate the interactions of triplets of atoms from those of quadruples, we assume that the energy of triplets of interacting atoms depends only on the characteristics of a triangle whose vertices are the centers of gravity of interacting atoms. In this model, the internal energy must therefore be invariant upon rearrangement of the numbers of interacting atoms and any rotation of the triangle in isotropic space, P(3) × O(3). To specify the form of energy dependence on characteristics of selected triangles, we constructed an integral rational basis of invariants in dependence on the components of the vectors connecting the vertices of each triangle. Using the example of a simple dependence of the energy on basic invariants, we show how to move from the assumed energy dependence on invariants to the dependence of energy on lattice sums.     

Effect on zero drift of accuracy of reciprocal tuning of elements of fiber-optic interferometer

The effect of the accuracy of reciprocal tuning of the elements of a fiber-optic interferometer (FOI) — laser, polarizer, and eigenaxes of single-mode-fiber (SMF) birefringence — is examined. It is shown that zero drift in the FOI consists of two parts — a constant part and a temperature-related variable part. Both of these parts are functions of the polarization state of the radiation at the entrance to the polarizer, the extinction coefficient of the polarized, and the orientation of the SMF eigenaxes with respect to the polarizer. The variable part of the zero drift is also a function of the birefringence and h-parameter of the SMF and the width of the radiation-source spectrum. Numerical estimates of FOI zero drift are made.Institute of Applied Physics, Academy of Sciences of the USSR. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 7, pp. 817–824, July, 1991.     

Kinetics of Macrolocalization Patterns of Plastic Flow of Metals

The features of the macroscopic inhomogeneity of plastic deformation in the form of autowaves with a pulsating amplitude are analyzed, and data on the localization of sources of acoustic emission at different stages of plastic flow in the stretching of fcc mono- and polycrystals are presented. The relationship between the local components of the plastic distortion tensor in the strain localization zone is traced. The role of acoustic phenomena accompanying the localization of plastic strain in the development of the process of plastic deformation is considered.     

Mechanisms of sublimation of silicon

An atomic modelling of the processes of desorption permits the determination of the energetically more favourable mechanisms of sublimation from a Si(111) surface. These include the creation of multi-vacancies, the presence of steps and the migration of atoms near the surface.     

Symmetry of Lagrangians of nonholonomic systems of non-Chetaev’s type

This paper studies the symmetry of Lagrangians of nonholonomic systems of non-Chetaev's type. First, the definition and the criterion of the symmetry of the system are given. Secondly, it obtains the condition under which there exists a conserved quantity and the form of the conserved quantity. Finally, an example is shown to illustrate the application of the result.     

Application of a method of linear scaling of frequencies in calculations of the normal vibrations of polyatomic molecules

The frequencies of the harmonic vibrations of 88 compounds consisting of atoms of the first period are calculated in the approximation of the hybrid density functional B3LYP with the 6-31G* basis set. Using 1189 frequencies from experimental IR and Raman spectra of these compounds in the gas phase and the corresponding theoretical frequencies, the coefficients of the function of linear scaling are found by the least squares method. The method of linear scaling of frequencies is applied to the prediction of the 108 vibrational frequencies of a porphin molecule. A conclusion is made that this method is promising for the interpretation of vibrational spectra of complex molecules and, in combination with the Pulay method of scaling of a quantum-mechanical field, for the determination of harmonic force constants.     

Model of stochastization of the oscillatory regime of superradiance

Based on the analysis of the experimental data on the observation of the fluorescence and superradiance of praseodymium ions in a matrix of lanthanum trifluoride, a model of superradiance of three-level radiators with two close upper levels is developed in the mean-field approximation and studied. The uppermost level is coherently pumped by an ultrashort pulse of electromagnetic field, after which the excitation is transferred to the close energy level, from which the superradiance transition occurs to the lower level. In limiting cases, the considered model is reduced to the known models of superradiance and describes the ordinary regimes of monopulse and multipulse (oscillatory) superradiance. However, in a certain region of parameters, the model under discussion describes such a multipulse superradiance signal in which electromagnetic field spikes composing it follow in time with random intervals and amplitudes, so that the regime of regular chaotic dynamics is demonstrated in a single superradiance signal. In a certain time interval, the proposed model can be described by the Lorenz equations with the parameters corresponding to the chaotic dynamics of spikes composing the superradiance signal. The presented results of the numerical simulation of the model equations qualitatively correspond to the picture of stochastic pulsations observed experimentally.     

X-ray interferometric method of determination of parameters of permolecular structure of polymers

A new method for determining the density of polymer materials based on determination of the path-length differences in moiré patterns is proposed. The method is characterized by simplicity and accuracy of results. The densities of polychloropren and polystirol have been determined with high accuracy. Knowledge of the dependence of the polymer density on the stretching degree enables one to reveal the dynamics of changes in the permolecular structure at deformation of polymers.     

Application of new methods of interpretation of meteor observations at the Institute of Astrophysics of Tajikistan

New methods of interpretation of meteor observations were developed and published in [1?C9]. The interpretation of ground-based observations of meteors and bolides available today in the scientific literature all over the world suffers from serious contradictions. Observers use the so-called photometric approach for determination of extra-atmospheric masses of meteoric bodies. This approach is based on the formula proposed in 1933 [10] and very simple ideas of how to describe the interaction between the atmospheric air and the surface of a meteoric body. These ideas are provisionally suitable to describe the flow around a body in a free molecular regime. Subsequently, the photometric approach was applied to all the meteor events including bolides. The main effort aimed to elaborate the approach included a choice of new formulas for the radiative efficiency.