Faculty of Physics
M.V.Lomonosov Moscow State University

## Formation of crystal structures in microgravitational conditions

### N.B. Brandt, A.G. Belov, L.I. Devyatkova, G.S. Zhdanov, V.V. Zubenko, Y.G. Karavaev, V.V. Moshchalkov, N.R. Nurtdinov, G.N. Ronaifii, I.V. Telegina, M.V. Chukichev, T.D. Shcherbatova, A.B. Yunovich

Moscow University Physics Bulletin 1983. 38. N 1. P. 1

The structure and some physical properties of a series of solid structures, eutectic compositions, and epitaxial layers are investigated. The study is performed on samples grown under conditions of microgravitation, in comparison with samples obtained under terrestrial conditions. Methods of optical and electron-raster spectroscopy, X-ray structural, and X-ray spectral analysis, photoluminescence, and cathode luminescence are used; quantum oscillational and optical effects are investigated. Certain peculiarities in the formation of the crystal and electronic structure of the material are observed.

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## Properties of multilayer interference absorber with, oblique incidence of radiation

Moscow University Physics Bulletin 1983. 38. N 1. P. 7

The angular properties of a multilayer interference absorber (MIA) are theoretically investigated. It is shown that, with inclination of the MIA, its resonant curve is shifted into the short-wave region, and the magnitude of the shift is proportional to the square of the angle of incidence of the radiation. A simple expression is obtained, describing the form of the central lobe of the MIA directionality diagram. The laws for the suppression of external noise in receivers with MIA at the inlet are discussed, together with the possibilities of tuning these receivers with respect to the resonant frequency following from the MIA angular properties.

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## Types of root trajectory of linear and linearized fourthorder systems

### G.A. Bendrikov, V.I. Miftakhov

Moscow University Physics Bulletin 1983. 38. N 1. P. 11

The root hodographs of fourth-order systems described by the characteristic equation $(a_0p^4+a_1p^3+a_2p^2+a_3p+a_4) +К=0$ are considered. In the plane of the two parameters M and N, which are functions of $a_i$, regions determining all the possible types of root trajectory are isolated. From the analysis of types of hodographs, the general dynamic properties of such systems are established, allowing their investigation and calculation to be simplified.

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## Spectra of nascent wind waves

### G.E. Kononkova, К.V. Pokazeev

Moscow University Physics Bulletin 1983. 38. N 1. P. 16

The spectra of wind undulation with startup distances of less than 4 m and dynamic velocities of 35 to 90 cm/sec are considered. The difference in the dependence of the spectra on the dynamic velocity and frequency under these conditions in comparison with the spectra of wave disturbance at large distances is explained by the action of drift flow.

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## Structure of triple dislocation points forming in the course of dislocational reactions in hcp crystals

### G.V. Bushueva, E.M. Yakhshaatova

Moscow University Physics Bulletin 1983. 38. N 1. P. 21

The moment method is used to investigate the structure and stability of triple spatial dislocational points in hep crystals. It is shown that the moment method offers the possibility of more rigorous estimation of the conditions of occurrence of dislocational reactions than the Frank criterion. The "moment" criterion allows the region of guaranteed occurrence of dislocational reactions to be determined, i.e., the region of mutual orientations of the dislocations for which the occurrence of reactions between them is favorable.

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## Electrostatic acceleration of a modulated electron beam

### Yu.K. Alekseev, A.I. Kostienko

Moscow University Physics Bulletin 1983. 38. N 1. P. 28

The problem of pumping power into a modulated electron flux is considered. It is shown that, with dynamic modulation of the flux, power pumping leads to slowing of the grouping process and reduction in beam efficiency. In the case of electrostatic control of the current's form however, its spectral composition and electron efficiency are retained.

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## Determining the plasma potential from the ionic part of the volt-ampere characteristic of an electrical probe

### V.S. Nikolaev

Moscow University Physics Bulletin 1983. 38. N 1. P. 32

A method of determining the plasma potential is proposed, on the basis of the ionic part of the volt-ampere characteristic of an electric probe.

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## Inhomogeneous magnetic state in the system of solid solutions $(1-x)$Cu$_{0,5}$Al$_{0,5}$Cr$_2$S$_4$-$x$CuCr$_2$S$_4$

### L.I. Koroleva, A.I. Kuz'minykh, I.V. Gordeev, Ya.A. Kesler

Moscow University Physics Bulletin 1983. 38. N 1. P. 38

The magnetic and electrical properties of the system of solid solutions $(1-x)$Cu$_{0,5}$Al$_{0,5}$Cr$_2$S$_4$-$x$CuCr$_2$S$_4$ are studied. All the compositions studied have semiconductor conductivity of $p$ type. The dependence of the magnetization on the field strength is a superposition of the magnetization characteristic for an antiferromagnet and the small spontaneous magnetization. The spontaneous moment corresponding to one impurity ion Cu$^{2+}$ is close to the magnetization of the ferromagnetic cluster Cr$^{3+}$ formed by Cr ions, the nearest neighbors of Cu$^{2+}$. It is suggested that these clusters (ferrons) are created by localization of holes around the acceptor copper ion because of the energy gain of $s$-$d$ exchange. The presence of ferrons in these materials is also confirmed by the sharp rise in paramagnetic susceptibility in the region of the Curie point. Estimates of the magnitude of $s$-$d$ exchange in these materials are given.

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## Two-photon absorption cross section at $F_{2}^{+}$ centers of alkalihalide crystals

### V.F. Kamalov, Yu.P. Svirko

Moscow University Physics Bulletin 1983. 38. N 1. P. 43

The nonlinear optical susceptibilities of $F_{2}^{+}$ centers in alkali-halide crystals are calculated. Values of the energy and dipole moments of transitions determined within the framework of the model of the molecular hydrogen ion allow the two-photon absorption cross section of a series of optical transitions.

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## Light reflection from the interface of media with thermal nonlinearity

### S.P. Chernov, A.V. Shepelev

Moscow University Physics Bulletin 1983. 38. N 1. P. 47

Consideration is given to nonlinear thermal reflection, which consists in change in the Presnel reflection coefficient with heating of the interface by radiation. A theory of this effect is proposed, and results are given of its experimental investigation and application for resonator Q-factor modulation. The possibility of using the effect for the anodization of radiation is discussed.

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## Measuring the energy characteristics of a sound field in an interferometer

### A.N. Ivannikov, F.Y. Rozhin, O.S. Tonakanov

Moscow University Physics Bulletin 1983. 38. N 1. P. 54

The basic relations characterizing the parameters of a sound field in an interferometer are considered. An experimental apparatus and procedure is described, allowing the characteristics of the reflective surface to be described on the basis of measurements of the power flux density.

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## Slow fluctuations in the cyclical magnetic reversal of thin magnetic films

### A.M. Buz'ко, V.Y. Potemkin

Moscow University Physics Bulletin 1983. 38. N 1. P. 60

A theoretical analysis is made of noise of type $1/f^{\alpha}$ arising in the cyclical - magnetic reversal of ferromagnetic films. On the basis of the idea that, in the course of magnetic reversal without saturation of the sample, there is slow variation in the magnitude of the film; volume undergoing magnetic reversal per cycle and also its "switching" moments, an expression is found for the spectral density of the fluctuations of the magnetization, describing the rise in spectral density of the magnetic noise close to frequencies which are multiples of the pumping frequency.

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## Some periodicities of atmospheric circulation

### A.Kh. Khrgian, E.D. Astakhova

Moscow University Physics Bulletin 1983. 38. N 1. P. 66

On the basis of generalization of much statistical material, the periodicity of atmospheric circulation is studied in various regions of the terrestrial globe at three basic isobaric surfaces (10, 30, and 500 mbar). It is shown that zonal circulation varies with a period of 27 days at the 10- and 30-mbar levels and with a period of 25 days at all the levels investigated. An attempt is made to explain a series of the results obtained on the basis of the hypothesis of solar action on the atmospheric circulation and also taking account of the superposition of oscillations.

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## Equations of motion of the two-body problem with variable masses

### L.G. Luk'yanov

Moscow University Physics Bulletin 1983. 38. N 1. P. 72

The question of reducing the equations of the general problem to the equations of relative motion is considered. The most general form of the equations of relative motion is obtained using the momentum integral.

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## Electromodulation spectra of high-resistance p and n GaAs doped with chromium

### V.A. Morozova, V.V. Ostroborodova

Moscow University Physics Bulletin 1983. 38. N 1. P. 77

From the electromodulation spectra of high-resistance p and n GaAs doped with chromium, the ionization energies of the acceptor levels of chromium are determined. They are $\varepsilon_{1 A V}= 0,61\pm 0,01$ eV and $\varepsilon_{2 A V} = 0,870 \pm 0,005$ eV and are independent of the temperature in the range 80-300K.

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## Relativistic inert-mass tensor

### G.Yu. Bogoslovskii

Moscow University Physics Bulletin 1983. 38. N 1. P. 81

Within the framework of the relativistic theory of anisotropic space - time, an explicit expression is found for the relativistic inert-mass tensor in terms of the field values determining the local spatial anisotropy and the isolated direction. Here, in accordance with the initial idea of Dicke, the dependence of the inertia on the localization of the body and the direction in space is found to be universal, and identical for all bodies that are in identical states.

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## Matching of high-Q gravitational antenna with the resonator of a capacitative oscillation transducer

### A.D. Kochubei, V.P. Mitrofanov

Moscow University Physics Bulletin 1983. 38. N 1. P. 84

A capacitative oscillation transducer of parametric type with VHF pumping is used to measure the limitingly small antenna oscillations in a gravitational-wave experiment. A matching scheme for a high Q antenna and a transducer resonator that is stable to seismic perturbation is considered.

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## Free parameter of spinel structure and M$\stackrel{..}{o}$ssbauer lineshift

### V.I. Nikolaev, V.S. Rusakov, N.I. Chistyakova

Moscow University Physics Bulletin 1983. 38. N 1. P. 87

The dependence of the M$\stackrel{..}{o}$ssbauer lineshift $\delta$ in oxygen ferrite - spinels on the free parameter of the structure u is considered. It is shown that the mutual disposition of the lines for the A and B points in the spectrum depends significantly on the oxygen parameter u. Within the framework of the field theory of ligands, theoretical dependences are obtained for the difference in the shifts $\Delta\delta^{ВА} = \delta^B — \delta^A$ as a function of u, at various values of the lattice parameter a. This difference is expedient for comparison with experimental data, since it does not depend on the choice of radiation source and scarcely depends on a. The available experimental data for ferrite - spinels with $Fe^{3+}$ ions at points A and B are found to be in agreement with the results of the calculations. In particular, the trend of the difference $\Delta\delta^{BA}$ to sign reversal with rise in u is confirmed. According to the results of the calculations, sign reversal should be observed at $u= u_{кр} = 0.3845$ for the case when $a=8.30 \stackrel{o}{A}$.

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## Self-correlation functions of rotational and translational motion in simple fluids

### O.P. Revokatov, N.V. Brilliantov

Moscow University Physics Bulletin 1983. 38. N 1. P. 90

A model in which the motion of a molecule is regarded as a sequence of free paths and strong multiparticle collisions is proposed. The result of collision is characterized by conditional probability functions. The analytical expressions obtained for the self-correlation functions are in good agreement with machine experiments.

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## Theory of radiation in media with changing anisotropy

### V.A. Davydov

Moscow University Physics Bulletin 1983. 38. N 1. P. 94

The radiation of a charge moving in a crystal with periodic change in direction of the optical axis over time is considered. Polarizational, angular, and spectral characteristics of the radiation are obtained and investigated.

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## Approximating-Hamiltonian method and the generalized Mayer theorem

### A.P. Bakulev

Moscow University Physics Bulletin 1983. 38. N 1. P. 98

A generalization of the Mayer theorem and its application to the approximating-Hamiltonian method are considered; an improved estimate is derived for the closeness of the free energies of the model and approximating systems; the advantages of the approach developed here is discussed for the example of a specific model.

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## Absorber theory for the Einstein equations in the first approximation

### A.Yu. Turygin

Moscow University Physics Bulletin 1983. 38. N 1. P. 101

The validity of absorber theory for the Einstein equations in the first approximation, within the framework of a static model of the Universe, is shown.

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## Resonant transitional scattering in vacuum in the presence of an external electromagnetic field

### V.R. Khalilov

Moscow University Physics Bulletin 1983. 38. N 1. P. 105

It is shown that the probability of scattering (in time $\tau$) of a strong, circularly polarized, electromagnetic wave with frequency doubling, propagating in vacuum in a periodic (in space) external electromagnetic field under difinite conditions, is proportional to $\tau^2$.

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## Neutral currents in the gage model $SU(3)_f\times U(1)$

### M.N. Dubinin

Moscow University Physics Bulletin 1983. 38. N 1. P. 108

A model of electrically weak interactions satisfying presently known experimental data on the process, taking neutral currents into account, is considered. Two neutral gage bosons with masses of the same order are introduced in the model.

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## Influence of the domain structure of the magnetostatic-oscillation spectrum of a ferrite plate

### S.A. Vyzulin, S.A. Kirov, N.E. Syr'ev

Moscow University Physics Bulletin 1983. 38. N 1. P. 111

The resonant frequencies of long-wave magnetostatic oscillations are calculated theoretically for a plate of a cubic magnet $(K_1<0)$ with a two-phase domain structure in the case of magnetization along the axis [110]. In the range 0.4-1.85 GHz, the spectrum of a YIG plate was investigated experimentally. Good agreement of theory and experiment is obtained both in the saturation region and in the field range where there is two-phase plate domain structure.

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