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Solid state physics

Vibronic effects in surface phases and molecular electronics

Vibronic effects in surface phases and molecular electronics

V.B. Zaitsev, A.V. Zoteev, V.F. Kiselev, G.S. Plotnikov

Moscow University Physics Bulletin 1992. 47. N 2. P. 4

In view of the fast progress in molecular electronics, much attention is being paid during recent years to systems combining the advantages of well studied basic elements of inorganic planar electronics and of elements of purely organic origin. In this work, experimental data are presented that point to the important role of vibronic effects in such structures. Considered are: (1) the role of vibronic effects in the events of trapping and recombination of charge carriers in the structures of semiconductor-insulator-adsorbed molecules, and also in photochemical transformations at the surface; (2) vibronic effects in the systems of semiconductor-insulator-dye molecules and semiconductor-insulator-Langmuir/Blodgett film; (3) some prospects for the utilization of vibronic effects in elements of molecular electronics.

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Theoretical and mathematical physics

Space-time topology as a consequence of the dynamics of closed superstrings

Space-time topology as a consequence of the dynamics of closed superstrings

N.F. Nelipa, M.Yu. Pekar

Moscow University Physics Bulletin 1992. 47. N 2. P. 18

The results obtained in the previous papers for a closed boson string are generalized to the case of a closed superstring.

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Isometric immersions of rotation metrics on a sphere into $E^4$ in the form of surfaces of revolution

Isometric immersions of rotation metrics on a sphere into $E^4$ in the form of surfaces of revolution

A.V. Bad'in

Moscow University Physics Bulletin 1992. 47. N 2. P. 22

In this paper, under investigation is the problem of immersion of a metric on $S^2$, which has the form $ds^2=g(r) (dr^2+r^2d\phi^2)$ in a certain stereographic projection, into $Е^4$ in the form of a surface of revolution with a pole. Denote the poles as $О_1$ and $O_2$. It is established that there exists an immersion in the class $C^1(S^2) \cap C^2(S^2\setminus (O_1\cup O_2))$. Some necessary and sufficient conditions are given for an immersion in the class $C^2(S^2)$. The deformability of the resulting surfaces in the same class is proved.

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Optics and spectroscopy

Dephasing parameters (time, decrement, and angle) and their dependence on pressure; dephasing deceleration and acceleration effects

Dephasing parameters (time, decrement, and angle) and their dependence on pressure; dephasing deceleration and acceleration effects

Yu.E. D'yakov

Moscow University Physics Bulletin 1992. 47. N 2. P. 27

A detailed mathematical description is developed for the dephasing time $\tau_{ph}$ as a function of pressure in different particle velocity correlation models. New polarization damping parameters (the dephasing decrement $m_{ph}$ and angle $\phi$ are introduced and their dependence on pressure is considered. The thresholds of the appearance of characteristic extrema (the Dicke dip, the peak of the function $\tau_{ph}$ etc.) are calculated for different substances. A "spectron" method is suggested for measuring the polarization damping spectrum using a single laser shot.

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The mechanism of origination of anomalous features in the structure of short-wavelength spectra of fluoride matrices doped with rare-earth ions

The mechanism of origination of anomalous features in the structure of short-wavelength spectra of fluoride matrices doped with rare-earth ions

K.M. Devyatkova, 0.N. lvanova, V.V. Mikhailin, S.P. Chernov

Moscow University Physics Bulletin 1992. 47. N 2. P. 40

A comparative study of the optical and structural parameters was performed for $BaY_2F_8$ and $KY_3F_{10}$ single crystals doped with $Er^{3+}$, $Но^{3+}$, $Yb^{2+,3+}$, and $Тm^{2+,3+}$ ions. An interrelation was established between the occurrence of regular structure imperfections in single crystals and the anomalies in their VUV spectra, which may be utilized to improve the luminescence parameters of the materials studied.

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Acoustics and molecular physics

Modern methods of perturbation theory for calculating hydroacoustic fields

Modern methods of perturbation theory for calculating hydroacoustic fields

V.A. Burov, S.N. Sergeev

Moscow University Physics Bulletin 1992. 47. N 2. P. 45

The perturbation theory methods for approximate solution of the Helmholtz equation governing the waveguide ocean model are discussed. Nonlinear perturbation theory, or the delinearization method, is introduced in addition to the standard perturbation theory modified in accord with the specificity of the acoustic problems. The new theory does not require the knowledge of the whole eigenvalue spectrum of the unperturbed problem and, besides, all the corrections are written explicitly in quadratures. Unlike the existing theories the approach suggested allows one to avoid nonremovable singularities in basic formulae for any waveguide types by choosing appropriate wavefunction representation in the form of polynomials.

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Geophysics

Estimation of heat flows from the ocean to the atmosphere in drop transport

Estimation of heat flows from the ocean to the atmosphere in drop transport

V.N. Aksenov, E.G. Andreev, I.N. Ivanova, M.R. Kuznetsova, I.N. Tkacheva, G.G. Khundzhua

Moscow University Physics Bulletin 1992. 47. N 2. P. 51

Estimations of heat flows from the ocean to the atmosphere in drop transport during storms are given. It is shown that: (1) heat transport by sprays generated by strong wind and wave collapse is insignificant, compared with turbulent transport; (2) sprays promote heat transport from the lower to the higher atmosphere.

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On the relation between the kinetic energy of pulsatory motion and the depth distribution of averaged velocities in a plane flow

On the relation between the kinetic energy of pulsatory motion and the depth distribution of averaged velocities in a plane flow

V.P. Petrov, Yu.L. Shchev'ev, A.S. Plakhov

Moscow University Physics Bulletin 1992. 47. N 2. P. 58

Studied was the depth distribution of terms of the balance equation of the kinetic turbulent energy in a plane flow. The measurements were performed by the thermohydrometer (hot-wire) method in a measuring flume of a rectangular cross section. The experimental data were computer-processed with the use of statistic programs which enabled computing the Reynolds stress tensor components. Based on the hypothesis that, in the external layer of plane flows, a reduction of the momentum depends on the kinetic turbulent energy, an approximate equality of the von Karman parameter and the coefficient of mutual correlation between the longitudinal and vertical velocity components was obtained.

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Astronomy

Post-Newtonian approximation in relativistic gravitation theory with account of galactic rotation

Post-Newtonian approximation in relativistic gravitation theory with account of galactic rotation

A.A. Vlasov

Moscow University Physics Bulletin 1992. 47. N 2. P. 63

It is shown how the account of noninertiality of a coordinate system undergoing galactic rotation affects the post-Newtonian physics of bodies in the solar system.

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Solid state physics

Physical factors of the $\alpha\to\beta$ transformation kinetics in a palladium-hydrogen system

Physical factors of the $\alpha\to\beta$ transformation kinetics in a palladium-hydrogen system

G.P. Revkevich, A.I. Olemskoi, M.A. Knyazeva, A.A. Katsnel'son

Moscow University Physics Bulletin 1992. 47. N 2. P. 68

X-ray diffraction methods were used to study the kinetics of the $\alpha\to\beta$ transformation in Pd exposed to electrochemical saturation with hydrogen. It was established experimentally that the kinetics of the $\alpha\to\beta$ transformation in the Pd-H system is described by the Avraami-type equation containing time to the first power. The observed time dependence of the saturation is related to the fairly high rate of growth of $\beta$-phase nuclei in a bounded volume. The incubation period $t_0$ and the logarithmic rate $\gamma$ of growth of the $\beta$ phase fraction were found to depend on the crystallographic orientation of the regions with respect to the flux of H atoms.

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On the theory of frequency dependence of the conductivity of a strongly doped compensated semiconductor

On the theory of frequency dependence of the conductivity of a strongly doped compensated semiconductor

V.F. Shitikov

Moscow University Physics Bulletin 1992. 47. N 2. P. 74

It is established that in a broad frequency band the real part of the conductivity of a strongly doped compensated semiconductor is described by the $Re\sigma(\omega)\sim \omega^s$, where $s < 1$. The frequency and temperature dependence of the exponent $s$ is discussed.

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On the determination of interatomic correlation parameters in alloys with h.c.p. structure

On the determination of interatomic correlation parameters in alloys with h.c.p. structure

V.M. Silonov. 0.V. Kris'ko, P.A. Kashirin, N.P. Kashirina

Moscow University Physics Bulletin 1992. 47. N 2. P. 79

An additional term is obtained in the expression for the intensity of diffuse X-ray scattering for alloys with close radii of the neighboring coordination spheres. A technique is suggested for determining interatomic correlation parameters corresponding to these spheres.

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Theoretical and mathematical physics

Equations of state of a homogeneous phase in the approximation of expansion in powers of density

Equations of state of a homogeneous phase in the approximation of expansion in powers of density

I.P. Bazarov, P.N. Nikolaev

Moscow University Physics Bulletin 1992. 47. N 2. P. 82

In this paper, based on the authors' method, an analytic expression is suggesed for the equation of state. The behavior of a system of particles with Lennard Jones interaction potential near the critical point is analyzed.

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An exact solution for the light shell in the RGT type theory

An exact solution for the light shell in the RGT type theory

A.A. Vlasov

Moscow University Physics Bulletin 1992. 47. N 2. P. 85

An exact continuous solution is found for the light shell in the RGT type theory. It is shown that the solution is clearly nonstatic, which is what must be the case for any RGT theory.

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Radiophysics

Selective excitation of characteristic waves in the ionosphere

Selective excitation of characteristic waves in the ionosphere

Yu.V. Berezi, D.E. Ryzhov

Moscow University Physics Bulletin 1992. 47. N 2. P. 87

A method is developed and experiments are carried out for studying the possibility of selective excitation of characteristic waves in the ionosphere. The results of the experiment indicate that one characteristic wave can be excited steadily, and the ratio of the mean power values of the damped and undamped waves can be brought to 10. It is shown that the gain in the noise immunity when receiving such a single-mode signal, compared with the double-mode one, is 10-20 dB.

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Astronomy

On the regularity in the disposition of the planets in the Solar system

On the regularity in the disposition of the planets in the Solar system

E.V. Pavlova

Moscow University Physics Bulletin 1992. 47. N 2. P. 91

A comparative analysis of the regularity in the disposition of the planets of the Solar system and of Jupiter's satellites is carried out. The existence of characteristic time and space scales, defined by the fundamental constants, is postulated.

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Solid state physics

The concentration dependence of microstructure in Al-Mn alloys

The concentration dependence of microstructure in Al-Mn alloys

V.S. Stepanyuk, G.M. Kalibaeva, A.A. Katsnel'son

Moscow University Physics Bulletin 1992. 47. N 2. P. 95

Al-Mn alloys with Mn concentrations 14%, 18%, 22.5%, and 25% were modeled by the method of molecular dynamics. The microstructure of these alloys with different concentrations of Mn were found to differ substantially. The structure of all the alloys contained a high percentage of icosahedral microclusters, and the maximum number of the icosahedron-like structures was observed at a concentration of 22.5%.

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