Einkristalle von halbleitendem Kadmiumantimonid — CdSb

Zusammenfassung Aus halbleitendem Kadmiumantimonid (CdSb) wurden Einkristalle gezüchtet, und zwar durch freie Kristallisation der geimpften Schmelze in Form von Plättchen. Einkristalle von ausreichend großen Dimensionen wurden nach der modifizierten Methode von Czochralski zubereitet. Es wurde festgestellt, daß der Zerfall der Schmelze von CdSb im Verlaufe der Züchtung des Kristalls bei geeignet angeordneter Einrichtung auf die Eigenschaften des entstandenen Einkristalls keinen Einfluß nimmt.

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CdSb

CdSb , -, , - , . , CdSb .

     

Weak “phase transitions” in asymptotic properties of lattice sums

Two classes ofn-dimensional lattice sums are shown to exhibit a weak form of a phase transition in their asymptotic properties. Both classes depend on two parameters such that the leading term in an asymptotic limit of one parameter is independent of the structure of the lattice in one domain of the second parameter and dependent on the structure in an adjacent domain, with a boundary point, or transition temperature, between the two domains.     

Der Zusammenhang zwischen der magnetischen Suszeptibilität und der chemischen Bindung halbleitender Verbindungen mit Sphaleritstruktur

Zusammenfassung Auf Grund einer einfachen Vorstellung wird gezeigt, wie sich mit Hilfe der magnetischen Suszeptibilität bei halbleitenden Verbindungen von Sphaleritstruktur die Abweichung von der idealen Kovalenzbindung vergleichen läßt und wie man die Messung der magnetischen Suszeptibilität zur Abschätzung der Energie des verbotenen Bandes und umgekehrt verwenden kann. Gleichzeitig werden die bei Zimmertemperatur bestimmten Werte der molaren Suszeptibilität der Verbindungen ZnSe, CdTe, CuBr, AgI, CdS und ZnS angegeben.

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, . ZnSe, CdTe, CuBr, AgI, CdS ZnS .

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Der Autor ist Frau Dr. N. A. Gorjunova (Physikalisch-technisches Institut, Leningrad) und Herrn Dr. E. Klier (Mathematisch-physikalische Fakultät, Prag) für die Verleihung der Proben und Herrn P. Jansa (Institut für Festkörperphysik, Prag) für die Hilfe bei der Messung zu Dank verpflichtet.     

Information theory and the problem of molecular structure

Recently it has been shown that the classical stick and ball viewpoint of molecules is inconsistent with quantum theory (QT). We suggest an unusual reconciliation: The QT state is not a physical property, but instead reflects our state of knowledge about observable aspects of reality. We show how this perspective is nevertheless objective. Applied to molecules, the view permits structure to exist only when observable evidence is compatible with this feature. Typically one must replace the a priori model (in particular, the dynamical generator) with one consistent with the evidence. We show that such structure is stable in the context of first-order perturbation theory. We also indicate how dynamics can be inferred from scattering data—a process alternative to postulating (field-theoretic) models for environment.     

Influence of linear elastic stresses on dynamic magnetostriction of cold-rolled transformer steel

The anisotropy of dynamic magnetostriction is investigated without external stresses, in extension, and in compression. Results are obtained expressing the (B) dependence for constant elastic stresses and also — () for certain induction values. Oscillograph traces are taken of the (H) and B(H) hysteresis loops with the specimens under investigation in extension and compression.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 5, pp. 110–115, May, 1977.     

Field emission from a metal covered with a semiconducting layer: A model calculation

The electron field emission from a metal covered with a thin layer of a semiconductor with electron affinity and dielectric constant is considered. The model takes into account the metal-semiconductor (Schottky) barrier of height _b, the conduction current inside the semiconductor, and the band bending at the semiconductor-vacuum interface due to the external field penetration. For thick films under moderately high electric fields, the metal-semiconductor interface does not influence the emission behaviour whereas for thin films, the interface plays an important role, depending on the barrier heights. In particular, for /_b<^2/3 the I–V characteristics will, for strong fields, be dominated by the field emission process at the interface. In such cases important deviations from Fowler-Nordheim behaviour are found.     

Measurement of the refractive index and optical absorption spectra of epitaxial bismuth substituted yttrium iron garnet films at uv to near-ir wavelengths

Refractive-index and optical-absorption spectra of Bi-substituted yttrium iron garnet films, epitaxially grown by liquid-phase epitaxy, have been measured in the spectral regime 0.26 m1.9 m by thin-film interference for 0.52 m and by ellipsometry for0.52 m. The Y_3–x–y Bi _x Pb _y Fe_5–z Pt _z O₁₂ films contain bismuth in the range Ox 1.42, lead in the range 0.01 y0.08 and platinum in the range 0.005<=z0.03. There is satisfactory coincidence between the results from ellipsometry and thin-film interference in the overlapping wavelength region. The materials investigated are the same as reported earlier from this laboratory in ter mof their magnetic and magnetooptic properties.     

Determination of the Coefficient of Laser Radiation Reflection from Dielectric Targets in Vacuum

We present the results of experimental determination of the coefficients of laser radiation reflection (₁ 10.6 m and ₂ 1.06 m) from dielectric targets of complex chemical composition in vacuum with allowance for a regime of developed plasma formation.     

Surfaces and Peierls contours: 3-d wetting and 2-d Ising percolation

A natural model of a discrete random surface lying above a two-dimensional substrate is presented and analyzed. An identification of the level curves of the surface with the Peierls contours of Ising spin configurations leads to an exactly solvable free energy, with logarithmically divergent specific heat. The thermodynamic critical point is shown to be a wetting transition at which the surface height diverges. This is so even though the surface has no downward fingers and hence no entropic repulsion from the substrate.Dedicated to Roland DobrushinResearch supported in part by NSF Grant No. DMS-8514834 and AFOSR Contract No. F49620-86-C0130 under the U.R.I. program     

Methodological imperfection and formalizations of scientific activity

Any mathematical formalization of scientific activity allows for imperfections in the methodology that is formalized. These can be of three types, dirty, rotten, and dammed. Restricting mathematical attention to those methods that cannot be construed to be imperfect drastically reduces the class of objects that must be analyzed, and relates all other objects to these more regular ones. Examples are drawn from empirical logic.     

On the critical exponent for random walk intersections

The exponent _d for the probability of nonintersection of two random walks starting at the same point is considered. It is proved that 1/2<₂3/4. Monte Carlo simulations are done to suggest ₂=0.61 and ₃0.29.     

Feynman integral and complex classical trajectories

Let _t be an analytic solution of the Schrödinger equation with the initial condition . Let _t be the solution of the Schrödinger equation with the initial condition =, where is an analytic function. When 0, then _t (x) _t (x)¹ ( _t (x)), where _t (x) trajectory starting from x. We relate this result to Feynman's sum over trajectories and complex stochastic differential equations.     

ЗАВИСИМОСТЬ ПОЧЕРНЕ НИЯ ФОТОГРАФИЧЕСКОЙ ЭМУЛЬСИИ ОТ ЭНЕРГИИβ-ИЗЛУЧЕНИЯ

, - - . , - , , :³²P,³⁵S ⁹⁰Sr+⁹⁰Y.     

Nelson's symmetry and the infinite volume behavior of the vacuum inP(φ)2

LetH _l be the Hamiltonian in aP()₂ theory with sharp space cutoff in the interval (–l/2,l/2). LetE _l =inf(H _l ), (l)=–E _l /l, and let _l be the vacuum forH _l . discuss properties of (l) and _l . In particular, asl, there are finite constants <0 and such that (l), ((l)–)l, and hence (l)=+/l+o(l ^–1). Moreover exp(–c ₁ l) _{l 1}exp(–c ₂ l) forc ₁,c ₂ positive constants, where _{l 1} is theL ¹(Q, d₀) norm of ₁ with respect to the Fock vacuum measure. We also present a new proof of recent estimates of Glimm and Jaffe on local perturbations ofH _l in the infinite volume limit.Research sponsored by AFOSR under Contract No. F44620-71-C-0108.On leave from Istituto di Fisica Teorica, Universitá di Napoli and Istituto Nazionale di Fisica Nucleare, Sezione di Napoli.A. Sloan Foundation Fellow.     

ЛОКАЛЬНЫЕ КОЛЕБАНлЯ ДВУХАТОМНОЙ ЛлНЕЙНО Й ЦЕПОЧКл С ДЕФЕКТАМл

. n : , . npou u , n . n n npocm .     

Gentle perturbations

By introducing a specific type of perturbation,A, in the Hamiltonian, we define a class of gently perturbed states, ,A, of a canonical ensemble, . The perturbations are chosen so as to preserve a relationship of the form ,A constant ×. Applications in ergodic theory and phase transitions are described.     

К процессам в электро дных оБластях в силъноточных кратк овременных электрических разря дах

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On processes in electrode spaces of short-time high-intensity electric discharges

The conditions and causes of the interrupted emission of the vapours of the material of short-time high-intensity electric discharge electrodes are discussed on the basis of earlier and new observations.

     

Continuity of type-I intermittency from a measure-theoretical point of view

We study a simple dynamical system which displays a so-called type-I intermittency bifurcation. We determine the Bowen-Ruelle measure and prove that the expectation (g) of any continuous functiong and the Kolmogoroff-Sinai entropyh() are continuous functions of the bifurcation parameter. Therefore the transition is continuous from a measure-theoretical point of view. Those results could be generalized to any similar dynamical system.     

Peculiarities in the evolution of the BUM of stimulated radio emission of the ionosphere

We present measured spectral and dynamic characteristics of the broad upshifted maximum (BUM) in the spectrum of artificial ionospheric radio emission (AIRE). It is shown that BUM is already formed starting from pump-wave frequencies that are smaller by at least 10 kHz than the values of electron gyrofrequency harmonic nf_He determined by the disappearance of the principal downshifted maximum (DM) in AIRE spectrum. The characteristics of additional maxima in BUM spectrum, which are a multiple of its principal maximum, are studied. It is shown that the frequency of BUM intensity maximum does not depend on the pump-wave frequency and the characteristic times of its evolution increase sharply for f_PW close to nf_He. We discuss the possibility of existence of the fast and slow components in BUM spectrum, which have significantly different evolution times. Experimental results on BUM behavior for different regimes of ionosphere modification are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 39, No. 3, pp. 352–371, March, 1996.The authors thank the staff of the Sura heating facility for assistance in organizing and running the experiments. The Russian authors also thank the Russian Foundation for Fundamental Research (grants 94-02-03253a and 96-02-18659), Soros Foundation (grants R87000 and 020623), and Ministry of Science for financial support of this paper and the Sura heating facility.     

Light absorption in laser-heated cavities

The absorption of laser light in 0.25–1 mm diameter gold cavities, irradiated for the purpose of generating high-temperature blackbody radiation with intense laser radiation of either =0.44 m or =1.3 m wavelength, was investigated. For =0.44 m radiation the absorption exceeded 0.9 for all conditions, but dropped to only 0.3 for the smallest cavities irradiated at =1.3 m. Entrance hole and cavity filling with plasma seems important for the understanding of the observations.