ВЛИЯНИЕ СТАРЕНИЯ НА Э ЛЕКТРИЧЕСКИЕ СВОЙСТ ВА ПОЛУПРОВОДНИКОВОЙ С ИСТЕМЫ Bi2Te3-Bi2Se3

, Bi₂Te₃-Bi₂Se₃. , , , . .

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Influence of ageing on change in electrical properties of semiconducting systems of Bi₂Te₃-Bi₂Se₃

The paper describes the effect of ageing observed on a semiconducting system Bi₂Te₃ — Bi₂Se₃. It is shown that the change in electrical conductivity and thermoelectric force, which takes place during ageing, is caused by the change in concentration of the free electrons. The influence of this process on the efficiency of equipment employing the Peltier effect is analyzed.

     

The unitary bogoliubov transformation for a quantized scalar field in a friedman space-time

The time-dependent creation and annihilation operators for a complex scalar field, in a Friedmann space-time, defining particle states with respect to which the Hamiltonian is diagonal, are related by a Bogoliubov transformation to the creation and annihilation operators defined in strict analogy with the procedure carried out in Minkowski space. The Bogoliubov transformation is here written in terms of a unitary operator,U, and an expression for that operator is found via the generating functionF=i InU. The properties of the representation obtained by makingU act upon the state vector , to give a new state _U, are discussed. It is shown that the particle-number operator remains constant in such a picture so that the evolution of the system with time is clearly seen to depend upon the energy _k on the one hand, and upon the state vector _U on the other. Also, it is pointed out that this new representation permits the in and out states to be defined unambiguously.On leave of absence from Istituto de Fisica G. Galilei (Padova) and Istituto Nazionale di Fisica Nucleare (Sezione di Padova).     

Facile preparation of single-crystalline nanowires of γMnOOH and βMnO2

A facile method has been developed to synthesize single-crystalline manganese (oxyhydr)oxide nanowires. A pure phase of single-crystalline MnOOH nanowires with the lengths of several hundred nanometres to several micrometers and the diameters of 5–40 nm was synthesized by hydrothermal transformation of commercial granular - or MnO₂ in water, and single-crystalline MnO₂ and polycrystalline Mn₂O₃ nanowires formed after subsequent calcination at 300 and 600 °C of the as-prepared MnOOH nanostructures, respectively. These low-dimensional nanostructured materials may find novel properties and provide more possible applications in lithium batteries and catalysis. PACS 81.07.-b; 81.10.Dn; 81.16.Be     

Unified fields of analytic space-time-energy

An analytic gravitational fieldZ (Z ^y ) is shown to include electromagnetic phenomena. In an almost flat and almost static complex geometryds ² =zdzdz of four complex variables z=t, x, y, x the field equationsR Rz = –(U U – Z ) imply the conventional equations of motion and the conventional electromagnetic field equations to first order if =(Z ^v) and =(z ) are expressed in terms of the conventional mass density function , the conventional charge density function , and a pressurep as follows: v=const=p/c ²–10^–29 gm/cm³.     

Asymptotic behaviour of spin-momentum distribution observables for fermion fields with cut-off self-coupling

In a previous paper asymptotic creation and annhilation operatorsa _± ^# have been constructed by the Kato-Mugibayashi method from the creation and annihilation operatorsa ^# for spin 1/2 fields with an interaction Hamiltonian density which is an evendegree polynomial in the field with ultra-violet cut-off and its derivatives. For any eigenvector of the total HamiltonianH=H ₀+H _I partial isometries _± have been defined so thata _± ^# equal _± a ^# *_± on the ranges _± of _±. Since the existence of a groundstate ofH has been proved, the existence of at least one pair _± follows. The purpose of this paper is to show that for any _± orthogonal to the distribution of spins and momenta of the interacting Schrödinger states exp[–itH]_± approaches fort the distributions of spins and momenta of the free state exp[–itH ₀] if a wave-amplitude renormalization is carried out in _±. This is achieved by studying the expectation values of the operators in themaximally abelian W*-algebra generated by operators of the form a*a, in terms of whichany information about spins and momenta can be expressed.Supported in part by the National Research Council of Canada.     

Self-diffusion in simple models: Systems with long-range jumps

We review some exact results for the motion of a tagged particle in simple models. Then, we study the density dependence of the self-diffusion coefficientD _N() in lattice systems with simple symmetric exclusion in which the particles can jump, with equal rates, to a set ofN neighboring sites. We obtain positive upper and lower bounds onF _N()=N{(1–)–[D_N()/D_N(0)]}/[(1–)]x for [0, 1]. Computer simulations for the square, triangular, and one-dimensional lattices suggest thatF _N becomes effectively independent ofN forN20.     

A sensitive non-destructive method for measuring the Nd doping concentration in Nd : YAG with high spatial resolution

This paper reports on an experimental method for measuring in Nd:YAG the Nd doping concentration (C) with high sensitivity (0.01 at.%Nd) and high spatial resolution (50 m). The method is based on the measurement of the fluorescence lifetime _f of the upper Nd laser level. Additional parameters required to determine C are the intrinsic fluorescence lifetime ₀ and the quenching parameter Q. The measured values of _f, ₀ (256.47±0.14 s) and Q (4.45±0.40×10²⁰ cm^-3) allow us to calculate the Nd concentration C with an absolute accuracy of 0.1 at.%Nd. By using this method C is measured at the outer surfaces of standard laser rods and at the faces of boule slices (with diameters of up to 50 mm). The obtained results demonstrate a detection sensitivity of 0.01 at.%Nd. PACS 42.70.Hj; 81.70.Fy     

Thes-f model with Coulomb repulsion: Thermodynamics of two atomic cluster. Spin 1/2

A cluster of two atoms described by thes-f model with Coulomb repulsion has been considered. The interaction between localized 4f electrons (S=1/2) is taken in the molecular field approximation. The thermodynamic quantities like magnetization, specific heat and correlation functions n , n , S ^z n , S ^z n , S ^z (n –n ), n n and S ⁺ a ⁺ a as functions of temperature are presented for different band fillingN=0, 0.5, 1, 1.5, 2. The dependence of Curie temperature onN is calculated. The phase diagram forN=1 (T=0K) shows the possibility of existence of two phases: paramagnetic and ferromagnetic.The Curie temperature and the specific heat as functions ofN exhibit similar trends as found in experiments on doped magnetic semiconductors.     

Influence of Hydrothermal Temperature on Structures and Photovoltaic Properties of SnO2 Nanoparticles

Two SnO₂ nanoparticles were synthesized by hydrothermal method at 170°C and 180°C, respectively. Transmission electron microscope observations reveal that the diameters of both the nanoparticles are around 6nm. At the same time, surface photovoltage spectroscopy measurements show that the nanoparticle synthesized at 180°C has more surface electronic states at 0.3eV below the conduction band than the one synthesized at 170°C. This means that the temperatures chosen in hydrothermal synthesis have significant influence on the surface electronic characteristics of resultant SnO² nanoparticles but the effect on their sizes is not obvious. However, after being calcined at 500°C for 2h, the diameter of the nanoparticle synthesized at 180°C increased to 23nm and that of the nanoparticle synthesized at 170°C increased to 32nm as calculated from X-ray diffraction pattern.     

Fock representations of the affine Lie algebraA 1 (1)

The aim of this note is to show that the affine Lie algebraA ₁ ⁽¹⁾ has a natural family _, ,v of Fock representations on the spaceC[x _i,y _j;i andj ], parametrized by (,v) C ². By corresponding the highest weight _, of _, to each (,), the parameter spaceC ₂ forms a double cover of the weight spaceC₀C –₁ with singularities at linear forms of level –2; this number is (–1)-times the dual Coxeter number. Our results contain explicit realizations of irreducible non-integrable highest wieghtA ₁ ⁽¹⁾ -modules for generic (,v).     

Измерение некоторых нейтронных спектров методом ядерных эмулъсий

. Ra+Be . , , . 8.     

Zur Temperaturabhängigkeit einiger Kenngrössen der Verfestigungskurven von Zinkeinkristallen

Zusammenfassung Es werden Ergebnisse beschrieben über die Temperaturabhängigkeit: der kritischen Schubspannung ₀, des Verfestigungskoeffizienten _A , im BereichA der Verfestigungskurve; des Verfestigungskoeffizienten _B im BereichB, der Längea _A des BereichsA und der Schubspannung _A am Ende des BereichsA. Die kritische Schubspannung wächst im Temperaturbereich 225–344°K linear mit abnehmender Temperatur. Der Temperaturverlauf des Verfestigungskoeffizienten _A , stimmt überein mit älteren Messungen an h.k.p. Metallen. Ähnlich verhält sich der Verfestigungskoeffizient _B . Die Schubspannung am Ende des BereichsA wird durch thermisch aktivierte Vorgänge beeinflußt. Der BereichA verkürzt sich im Temperaturbereich 0–85°C linear mit zunehmender Temperatur. Temperaturwechselversuche zeigen, daß im BereichB thermisch irreversible Änderungen in der Versetzungsstruktur auftreten.

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: ₀, _A , _B , _{A A} . 226 344°K . _A . _B . . 0–85°C . , .

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Herrn Dr. F. Kroupa und Ing. B. esták bin ich für das Durchlesen des Manuskripts sowie wertvolle Hinweise zu Dank verpflichtet. Mein besonderer Dank für zahlreiche fruchtbare Diskusionen und Anregungen gilt Herrn P. Kratochvíl. Herrn Prof. Dr. A. Seeger danke ich ganz besonders für Kritik des Manuskripts und wertvolle Ratschläge.     

Les absorbants de son resonants

Résumé Dans la présente étude, on trouve un bref résumé des travaux de l'auteur, de ses collègues et collaborateurs, concernant l'utilisation des résonateurs dans l'acoustique architecturale. On explique tout d'abord le problème de l'inpluence des résonateurs sur la durée de la réverbération des salles. Se basant sur des considérations théoriques, l'auteur déduit le critère de l'emplacement le plus favorable des matières absorbant le son dans le résonateur même et discute la possibilité de l'absorption totale du son par le résonateur. Dans le cas des systèmes de résonateurs pareils disposés régulièrement sur les murs, le diapason pouvant être obtenu d'une importante absorption est relativement faible. En se servant de systèmes résonants d'absorption comportant plusieurs couches de résonateurs, reliés en série, le diapason de l'absorption importante peut être notablement élargi. L'auteur explique la corrélation du coefficient d'absorption et de l'angle d'incidence de l'onde sonore. En conclusion, on mentionne des exemples de l'utilisation pratique des résonateurs d'absorption les plus simples pour obtenir la caractéristique de l'absorption de fréquence exigée. On discute aussi le problème de l'influence des vibrations simultanées de la paroi extérieure du système de résonance sur la caractéristique de l'absorption du son.

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. . . , , . , , . . ; .

     

ВЛИЯНИЕ ПРЕДВАРИТЕЛ ЬНОГО ОСВЕЩЕНИЯ ha ХАРАКТЕРИСТИКИ МЕДН ОЗАКИСНЫХ ВЫПРЯМИТЕ ЛЕЙ

, 150° , . - . -. . ( ).     

Exact expressions for row correlation functions in the isotropicd=2 ising model

We present exact explicit expressions for the row spin-spin correlation functions _{00 n}0 in the isotropicd= 2 Ising model, in terms of elliptic integrals, forn 5. We also give a general structural formula for _{00 n}0.     

Tunable UV radiation at short wavelengths (188–240 nm) generated by sum-frequency mixing in lithium borate

Sum-frequency mixing (₃=₁+₂) of UV laser radiation (₁=266 nm and 213 nm) and tunable coherent infrared light (₂=1.2–2.6 m) in lithium borate (LBO) generates radiation at short wavelengths (₃=188–242 nm). The UV radiation at ₁ is produced by the fourth and fifth harmonic of a pulsed Nd-YAG laser. The infrared light is generated with an optical parametric oscillator of beta barium borate. The phase-matching angle is measured as function of ₃ and compared with calculated values. For UV laser radiation at shorter wavelengths (173 nm₁213 nm) the calculations predict an extension of the tuning range of the sum-frequency generated at ₃ to wavelengths as short as the LBO transmission cutoff at 160 nm.     

Ermüdungserscheinungen der infrarotbestrahlten Silber-Cäsium-Photokathoden

Zusammenfassung In dieser Arbeit werden die Erscheinungen der normalen und anomalen, durch Infrarotstrahlung verursachten und von uns schon früher an diesen Photokatoden beobachteten Ermüdung von Silber-Cäsium-Photokathoden untersucht. Diese Erscheinungen wurden an durchsichtigen sowie undurchsichtigen, durch verschiedene Technologien zubereiteten Photokathoden festgestellt. Es wurden Messungen der Strahlungsintensitäts-, Temperatur- und Spektralverteilungsabhängigkeit der normalen und anomalen Ermüdung durchgeführt. Es werden die Ursachen der Unübereinstimmigkeit im Vergleich mit Arbeiten von De Boer und Teves besprochen. Ferner wurden die Zeitverläufe der Ermüdung bei der Abwechslung der Bestrahlungs- und Dunkelzyklen studiert.

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, , . , . , . . .

     

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.     

Method of moments in analysis of x-ray diffraction lines

A general relation between the moments of the functionsf,g, andh, in the integral equationh(x)=f(y)g(x–y) dy, is derived. This enables any moment of the unknown functionf to be calculated from the moments of the functionsg andh. In particular, if certain assumptions are fulfilled, the moments of the components of the doublet can be calculated with advantage from the moments of the total profile. The statistical significance of the moment characteristics is also emphasized.

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f, g, h h(x)=f(y)g(x–) dy, f g h. , . .