Faculty of Physics
M.V.Lomonosov Moscow State University
Theoretical and mathematical physics

## Weakly bound states of а two - particle system in an external field

### V.V. Komarov, А.М. Popova, and V.G. Airapetyan

Moscow University Physics Bulletin 1989. 1989. N 1. P. 1

А method is proposed for estimating the number of weakly bound states of the energy operator of а system of two quantum- mechanical particles in an external field.

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Atomic and nuclear physics

## Resonant photoionization of helium- like ions in the region between the second and third thresholds. Helium- like lithium

### S.М. Burkov, N.А. Letyaev, and S.I. Strakhova

Moscow University Physics Bulletin 1989. 1989. N 1. P. 5

Calculations are reported of the total and partial cross sections for the photoionization of the ion $Li^+$, the parameters of resonances in the total and partial cross sections, the anisotropy coefficient of the angular distributian of photoelectrons, and the alignment of the ion $Li^{+ +}$ in the n = 2 state in the region between the second and third thresholds.

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## Rydberg atoms and the production of monodirectional electrons

### V.А. Namiot and Е.Р. Skorokhod

Moscow University Physics Bulletin 1989. 1989. N 1. P. 10

It is shown that, under certain definite conditions, electrons producedmas а result of the ionization of Rydberg atoms сап bе highly monochromatic and have а very small angular spread.

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## Stochastic modulation in а circuit incorporating an MIS structure and exposed to light

### V.F. Marchenko

Moscow University Physics Bulletin 1989. 1989. N 1. P. 13

The mechanism responsible for stochastic modulation in а resonant circuit in which the capacitance is an MIS structure exposed to light is discus sed. The presence of stochastic oscillations has been confirmed experimentally at points at which the resonance curve is multivalued.

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## Range of validity of the geometric - optics approximation in randomly inhomogeneous media

### V.D. Gusev, Е.V. Petukhova, and L.I. Prikhod'ko

Moscow University Physics Bulletin 1989. 1989. N 1. P. 16

The condition of noncrossing rays is used to develop а new criterionfor the validity of the geometric-optics approximation in randomly inhomogeneous media. The condition obtained extends the possibilities of the method in the solution of scattering problems.

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## Parametric conversion of microwave and ultrasound in $KTaO_3$ dielectric resonators

### G.V. Belokopytov, I.V. Ivanov, V.N. Semenenko, and V.А. Chistyaev

Moscow University Physics Bulletin 1989. 1989. N 1. P. 20

Pararnetric electrostriction effects such as the conversion of ultrasound into microwa ves and the parametric amplification of microwaves has been produced experirnentally in potassiurn tantalate resonators.

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## Spatial resolution under the conditions of local catholuminescence inthe scanning electron microscope as а function of the electro-physical parameters of the sample

### А.R. Gareeva, V.I. Petrov, and G.А. Chizhov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 24

The point-source approximation is used to analyze the generation of electron-hole pairs in а semiconductor. It is shown that the spatial resolution depends not only on the diffusion length of minority carriers, but also on the rate of surface recombination and the absorption of radiation in the medium.

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Optics and spectroscopy

## Adaptive correction of phase distortion in а system with optical control

### М.А. Vorontsov, V.Yu. Ivanov, and А.N. Маtvееv

Moscow University Physics Bulletin 1989. 1989. N 1. P. 30

An adaptive system with optical control, using а nonlinear- optics phase analyzer, is discussed. The method of correction is shown to bе effective for both static and dynamic phase distortions.

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## Solution of the inverse problem of optimization of the phase characteristic of а dielectric deflector with electrooptic control

### N.Е. Shapkina

Moscow University Physics Bulletin 1989. 1989. N 1. P. 33

А method of improving the phase characteristics of а dielectric de flector with electrooptic control (the control electrodes are in the form of а bazed grating) is discussed. It is based on the solution of the inverse problem of correction of а traditional echelette.

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Acoustics and molecular physics

## Approximate analytic solution of the equations of collinear acoustooptic diffraction

### V.G. Zakharov and V.N. Parygin

Moscow University Physics Bulletin 1989. 1989. N 1. P. 38

An approximate analytic solution is found for the equations of collinear acoustooptic diffraction with allowance for the divergence of the acoustic beam when the diameter of the piezoelectric transducer is of the order of а few millimeters.

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## Thermoelastic generation of acoustic waves during nonlinear diffusion of photoexcited electron- hole plasma

### V.Е. Gusev

Moscow University Physics Bulletin 1989. 1989. N 1. P. 42

The possibility of optoacoustic determination of the diffusion length of nonequilibrium electron-hole plasma in а semiconductor is investigated.

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## Effect of multiple scattering in diffraction tomography: the T- matrix approach

### V.А. Burov, М.N. Rychagov, and А.V. Saskovets

Moscow University Physics Bulletin 1989. 1989. N 1. P. 48

An algorithm is developed for re constructing а refraction inhomogeneity from tomographic data, taking into account multiple scattering. The method relies on an iteration procedure applied to the Lippmann-Schwinger equation for the T-matrices. Problems associated with the interpolation of data in Fourier space are discussed.

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## Vortex structure and energy balance in mean motion in а channel with smooth walls

### V.Р. Petrov, V.I. Sugrei, and Yu.L. Shchev'ev

Moscow University Physics Bulletin 1989. 1989. N 1. P. 53

Experimental data are used as а basis for an analysis of the reasons for the loss of energy balance at а point. Regions in which turbulent energy is transformed from one form to another are identified and the dimensions of energy- bearing vortices in the flow are determined.

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## А study of mechanisms responsible for the polarization of liquid dielectrics in the electric field between conducting electrodes

### А.А. Belov, А.А. Usanov, and М.V. Shchetinin

Moscow University Physics Bulletin 1989. 1989. N 1. P. 59

The example of n - heptane is used to investigate the polarization of liquid dielectrics in the electric field between conducting electrodes. Polarization mechanisms with time constants in the range between 1 and $2\cdot 10^4$ sec were investigated.

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Solid state physics

## Hyperfine fields in $Gd(Fe_{1-x}M_x)_2$

### А.К. Kupriyanov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 62

It is shown that the "induced" fields acting on Gd are due to both the polarization of conduction electrons and additional exchange polarization of the atomic core of the ion of the rare earth metal. The latter is the result of the exchange interaction between the sublattices.

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## The properties of martensitic transformations of NiTi-V alloys as functions of aging

### А.G. Khundzhua, М.I. Zakharova, and G.N. Коkoev

Moscow University Physics Bulletin 1989. 1989. N 1. P. 69

X- Ray structure analysis of single-crystal samples were used to investigate martensitic transformations in NiTi-V alloys in the hardened state and after isothermal tempering at 623 К.

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Geophysics

## Analytic model of polydisperse back-scattering coeffic ient for problems in the laser diagnostics of the atmospheric aerosol

### V.L. Boichenko, Т.В. Razumikhina, V.I. Rozhdestvenskaya, and А.I. Kholodnykh

Moscow University Physics Bulletin 1989. 1989. N 1. P. 73

An approximate analytic expression is reported for the polydisperse back- scattering coefficient, obtained bу approximating the exact Mie back- scattering pattern, taking into account actual particle - size distribution functions.

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Theoretical and mathematical physics

## Quantum limit of the experimental error in the energy of а relaxing oscillator

### Yu.I. Vorontsov and I.V. Kobzar

Moscow University Physics Bulletin 1989. 1989. N 1. P. 77

The relaxation time of an oscillator during the process of energy measurement depends on the state of the measuring device , and this sets а fundamental limit on the experimental uncertainty in the measured energy of the oscillator.

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## Unsatisfactory definition of total energy in GTR formulated on а "flat background"

### А.А. Vlasov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 80

А simple example is used to show that the formulation of the general theory of relativity on а "flat background" cannot lead to а solution for the energy-momentum of the gravitational field.

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## Gravitational singularities of the caustic type

### G.А. Sardanashvili and Е.G. Timoshenko

Moscow University Physics Bulletin 1989. 1989. N 1. P. 83

А description is given of а new type of gravitational singularity which take s the form of space-time foliation caustics

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## History of quantum theory of radiation in Russia

### Т.V. Aleksakhina and В.I. Spasskii

Moscow University Physics Bulletin 1989. 1989. N 1. P. 86

The contribution of Russian physicists to the development of the quantum theory of radiation prior to the advent of quantum mechanics is examined. The first experimental confirmation of the theory of photons and theoretical studies of the connection between the quantum hypothesis and the Planck formula are discussed.

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## Spectral filtration of images using а tunable acoustooptic filter

### V.В. Voloshinov, L.А. Kulakov, and O.V. Mironov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 89

The filtration of images bу the acoustooptic method has been investigated in the optical wavelength range between 0.5 and 1.2 μm

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## Stimulated undulator radiation emitted Ьу а tubular electron beam

### Yu.I. Bogdanov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 92

The structure of the radiation field due to the tubular electron beam in а high-gain free-electron laser is discussed, taking diffraction into account.

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## Behavior of а Lorentz system under parametric interaction

### D.А. Gribkov and Yu.I. Kuznetsov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 95

The synchronization of chaotic oscillations of а Lorentz systern under pararnetric interactions is investigated. It is shown that the threshold rnodulation depth of the pararneters is а power- type function of the Kolrnogorov entropy.

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Optics and spectroscopy

## Variations in the spectral parameters of optical coatings for obliquely incident light

### N.V. Grishina and А.V. Tikhonra vov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 98

The statistical approach is used to estimate the effect of errors in the parameters of layers in two - component optical coatings on their spectral characteristics for obliquely incident light.

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Acoustics and molecular physics

## Rotational friction of biopolymers in solution

### V.Р. Denisov, V.V. Migulin, Yu.М. Petrusevich, and O.Р. Revokatov

Moscow University Physics Bulletin 1989. 1989. N 1. P. 102

It was demonstrated experimentally that electrostatic interactions between polymers and water have а strong effect on the viscosity of biopolymer solutions and on the rotational correlation time of macromolecules. The relationship between these parameters was investigated.

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Solid state physics

## Effect of an electric field on the conductivity of a - Si:H films with а high hydrogen concentration

### I.А. Kurova and Е.N. Ponarina

Moscow University Physics Bulletin 1989. 1989. N 1. P. 105

The increase in the conductivity of a - Si:H filrns detected for elec tric fields Е > 20 V/cm has been investigated. А rnodel of the effect is proposed.

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