Faculty of Physics
M.V. Lomonosov Moscow State University

# Issue 6, 1988

Theoretical and mathematical physics

## Oscillatory states of some nonlinear systems with distributed delay

### G.N. Medvedev and В.I. Morgunov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 1

An analysis is given of the nonlinear oscillations of the components of manipulator devices, taking into account their viscoelastic prop erties. An averaging procedure is used to calculate the small oscillations of manipulator components that accompany the programmed motion of the mechanism.

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Atomic and nuclear physics

## The effect of target density on the equilibrium charge composition of beams of fast helium ions

### N.F. Vorob'ev, V.Р. Zaikov, and Е.А. Kral'kina

Moscow University Physics Bulletin 1988. 1988. N 6. P. 6

А calculation is reported of the mean charge $\bar{i}$ and the charge fractions $F_i$. of an equilibrium beam of helium ions in high and low density media as functions of the charge $Z_t$ of the target nuclei in the range $1\le Z_t \le 24$ and ion velocities in the range $V_0\le V\le 3V_0$. It is shown that the functions $\bar{i}(Z_t)$ and $F_i(Z_t)$ may bе very different in low and high density targets.

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## Approximate analytic solution of the problem of the helium atom

### V.I. Zharikov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 10

The method of hyperspherical harmonic s is used to obtain an approximate analytic solution of the quantum- mechanical problem of the helium atom. The calculated ground- state energy differs from the exact value bу only 3,8%. The express ion for the wave function is reproduced.

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## Generalized effect of dynamic damping of noise in resonant measuring circuits

### . А. V. Gusev and V. N. Rudenko

Moscow University Physics Bulletin 1988. 1988. N 6. P. 13

The minimum noise in measuring circuits consisting of а test oscillator and а resonance electromechanical transducer is discussed. А formula is given for the amplitude of the threhold signal for large values of the electromechanical coupling coefficient.

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## An analysis of processes occurring in а nonautonomous auto stochastic system

### S.А. Afanas'ev, D.А. Gribkov, and Уu.I. Kuznetsov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 17

It is shown that а regular external disturbance outside synchronization regions leads to the smoothing of the spectral density of chaotic oscillations in auto-stochastic systems. Different scenarios of transition to chaos in а nonautonomous generator of chaotic oscillations that incorporates а tunnel diode are discussed.

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## Snergy approach to the desciption of transverse-mode generation in injection lasers

### А.S. Logginov and А.G. Rzhanov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 21

An analysis of the characteristic equation for the active waveguide of the injection laser with arbitrarily specified transverse geometry is used to derive and investigate the equation for the energy balance during transverse - mode generation.

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Optics and spectroscopy

## Characterization of defects observed in the scanning electron microscope in single -crystal $BaY_2F_8$ used in the vacuum ultraviolet

### К.М. Devyatkova, О.N. Ivanova, V.V. Mikhailin, T.B. Uvarova, and S.Р. Chernov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 26

Scanning electron microscopy was used to investigate the structure of single-crystal $BaY_2F_8$. The experirnental results indicate that the structure factor contributes to the optical spectra of the single crystals.

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## Numerical simulation of the plasma mirror produced on the surface of а semiconductor bу а picosecond pulse of adiation

### V.Т. Platonenko and O.Р. Popova

Moscow University Physics Bulletin 1988. 1988. N 6. P. 31

А numerical simulation is reported of the production of а plasma mirror on the surface of silicon bу picosecond laser pulses. The dependence of the mirror lifetime on the parameters of the exciting pulse and the properties of the silicon surface is discussed.

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## Determination of the probability of absorption of light in free -free transitions

### V.D. Kukin, V.S. Rostovskii, and N.Р. Yudin

Moscow University Physics Bulletin 1988. 1988. N 6. P. 38

The evaluation of the matrix element sof the electric dipole transition between states in the continuous spectrum is discussed. Recurrence relations are obtained for the contribution to the matrix elements of the integral evaluated over the region outside the atom in terms of the values of the wave functions and their derivatives on the boundary.

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## Spectral methods of determining acousto-optical diffraction bу а bounded sound beam

### M.А. Voronova and V.N. Parygin

Moscow University Physics Bulletin 1988. 1988. N 6. P. 43

The Bragg diffraction problem is solved for а bounded sound beam, using а new method employing а four- dimensional spectral representation of the light and sound beams.

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## Raman scattering of light in $\alpha$- quartz exposed to small doses of reactor and $\gamma$ - radiation

### L.Р. Avakyants, D.F. Keselev, and М.М. Firsova

Moscow University Physics Bulletin 1988. 1988. N 6. P. 50

The use of modern techniques in the investigation of Raman scattering in $\alpha$- quartz exposed to small reactor doses was used to separate the influence of neutron and $\gamma$ - components on the spectrum and to demonstrate the presence of а small frequency shift of the Raman lines.

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## Mirrors with а 180° phase difference at oblique incidence

### N.V. Grishina, А.V. Tikhonravov, and N.Е. Shapkina

Moscow University Physics Bulletin 1988. 1988. N 6. P. 54

The synthesis of reflecting coatings with а 180° phase difference between the s and р cornponents of the reflected field at an angle of incidence of 45° in the wavelength range $\Delta \lambda /\lambda=\pm 5 \%$ is discussed. Exarnples of synthesized systerns are reproduced.

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Geophysics

## Phase transitions and the magma formation problem

### М.V. Avdulov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 58

Periodic temperature variations are accompanied bу а separation of the Earth's mantle into mineralogical fractions at temperatures below the solidus point of rock. А physical model is put forward for the formation of magmatic melts of different chemical compositions.

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Solid state physics

## Inelastic scattering of X-rays in the case of diffraction bу crystals with а damaged surface layer

### V.А. Bushuev and Т. Сhen

Moscow University Physics Bulletin 1988. 1988. N 6. P. 64

А dynarnic theory of Cornpton and therrnal diffusion scattering during the diffraction of X-rays Ьу perfect crystals with an epitaxial filrn on the surface is developed.

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## Solitions in а domain wall

### L.I. Antonov, А.N. Matveev, and Р.А. Polyakov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 71

It is shown that а nonlinear dynamic structure such as а soliton can appear in the domain wall of а massive magnetic sample.

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## Effect of all- sided pressure on the magnetization of single crygtal terbium

### S.А. Nikitin and R.V. Bezdushnyi

Moscow University Physics Bulletin 1988. 1988. N 6. P. 76

The effect of all-sided pressure on the rnagnetization of single-crystal terЫurn is investigated. Giant volurne magnetostriction, $\sim 650\cdot 10^{-6}$, is found. The dependence of the magnetic anisotropy constant $K_6$ on pressure is found to bе described bу а single-ion theory of magnetic anisotropy.

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## Defect formation in GaAs and GaAsP under the influence of the excimer laser radiation

### А.I. Efimova, Р.К. Kashkarov, М.S. Dzhidzhoev, and V.К. Popov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 82

The effect of excimer-laser pulses on the photoluminescent properties of GaAs and GaAsP was investigated. It was shown that, depending on the initial defects present in the samples, the laser pulses give rise to the generation of annihilation of radiationless recombination centers.

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Theoretical and mathematical physics

## Reduction problems in the case of an unknown correlation operator

### Yu.Р. Pyt'evand M.L. Serdobol'skaya

Moscow University Physics Bulletin 1988. 1988. N 6. P. 87

An analysis is given of the reduction of experimental data for models with an а priori unknown correlation operator representing measurement uncertainties.

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## Deterioration in temporal coherence of а light pulse with random spatial modul ation in the case of time-dependent thermal self- interaction

### V.А. Aleshkevich, G.D. Kozhoridze, and А.N. Matveev

Moscow University Physics Bulletin 1988. 1988. N 6. P. 90

An analytic study is reported of the deterioration in the temporal coherence of а powerful light pulse that is randomly modulated in space during time-dependent thermal self-interaction. Expressions are obtained for the beam width, radius, and coherent time.

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## Measurement of the nonlinearity of liquid dielectrics in submicron gaps

### F.V. Bulygin and S.Р. Vyatchanin

Moscow University Physics Bulletin 1988. 1988. N 6. P. 94

А method has been developed for measuring а submicron capacitive gap and to determine its size without direct measurement. The quadratic dielectric nonlinearity of а number of liquid dielectrics has been measured for the first time in the microwave range.

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Optics and spectroscopy

## Application of the introscopic sensitive- point method to the stabilization of the spin oscillator using an inhomogeneously broadened line

### N.V. Anisimov and Yu.S. Konstantinov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 98

An application of the sensitive- point method to the staЫlization of the multifrequency output of а spin oscillator is discussed. The possible use of two-frequency gradient modulation in increasing the resolution of the NMR spectrometer is examined.

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Acoustics and molecular physics

## Classification of singular points of the streamlines of active and reactive intensity in the near field due to sources of sound

### А.N. Ivannikov and D.I. Kravchenko

Moscow University Physics Bulletin 1988. 1988. N 6. P. 101

А classification is given for the singular points of streamlines of the active and reactive intensity. It is shown that active intensity has singular points in the form of а center or saddle, whereas reactive intensity has singular points in the form of а node or saddle.

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## Theoretical desciption of thermal self- focusing of saw- tooth acoustic waves

### О.V. Rudenko and O.А. Sapozhnikov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 106

The geometric acoustic approximation used to analyze thermal selffocusing of saw-tooth waves. The analysis shows that the results differ significantly from those estaЬlished previously for harmonic waves.

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Geophysics

## Effect of а tropical cyclone on ocean surface

### V.V. Alekseev and N.S. Evsa

Moscow University Physics Bulletin 1988. 1988. N 6. P. 109

The reaction of ocean surface to а tropical cyclone (ТC) is discussed in terms of the "shallow water" model. The variation in the quasihomogeneous layer is described bу the Pollard model, and а distribution of the surface level of the ocean is obtained for different TC parameters.

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Solid state physics

## Galvanomagnetic effects in germanium- doped indium antimonide under deep irradiation with fast electrons

### N.В. Brandt, Е.Р. Skipetrov, V.V. Dmitriev, G.I. Kol'tsov, and Е.А. Ladygin

Moscow University Physics Bulletin 1988. 1988. N 6. P. 113

It is shown that p-n conversion under electron bombardment of $р-InSb\langle Ge\rangle$ samples, the electron concentration passes through а maximum, and а limiting state with n- type conductivity is reached. These re sults are explained in terms of the formation of complexes consisting of primary defects and impurity atoms.

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## Deformation mechanism for the metal- semiconductor phase-transit ion temperature of а $VO_2$ film due to absorption

### V.I. Emel'yanov, N.L. Levshin, and А.L. Semenov

Moscow University Physics Bulletin 1988. 1988. N 6. P. 117

А theoretical study is reported of the effect of absorption of molecules on the semiconductor- metal phase - transition temperature in $VO_2$ films. The theoretical predictions are compared with experimental data.

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## The state of dipolar glass in PbGeTeSe solid solutions produced along the PbSe- GeTe section of the phase diagram

### A.I. Lebedev and I.А. Sluchinskaya

Moscow University Physics Bulletin 1988. 1988. N 6. P. 121

Samples of $n-Pb_{1-x}Ge_xTe_{1-y}Se_y$ with $y\approx 1$ and germanium concentration below the threshold for the onset of ferroelectric properties were found to exhibit low- temperature electron scattering. This was explained bу the appearance of disordered dipolar structure of the dipole glass type in these systems.

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