What determinates the chemical changes of the internal conversion coefficients for inner atomic shells?

Calculations of internal conversion coefficients (ICC) of the E1–E4 and M1–M4 transitions for nuclei in ions show that the relative changes _i / _i of the ICC _i for deep inner subshells can differ significantly from the relative changes _i/_i of the electron densities _i at the nucleus. For the K conversion _i/ _i are many times greater than _i/_i. Especially large deviations of _i/ _i are characteristic of transitions of high multipolarity; however, for the M1 transitions they can also be significant. Illustrations of various dependencies of _i/ _iare presented for the conversion in the regionZ-50.     

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.     

ФИЗИЧЕСКИЕ ОСНОВЫ ИЗ МЕРЕНИЯ НАПРАВЛЕНИЯ ВОЗДУШНОГО ПОТОКА МЕ ТОДОМ НАКАЛЕННОЙ ПРО ВОЛОКИ ПРИ ВЫСОКНХ ПОДЗВУКО ВЫХ СКОРОСТЯХ

d - l - t _d R _max - J , ( ) - - , . . - ( ) - - R R _max —R. ,      

Second-harmonic generation at periodic second-order susceptibility gratings with self-phase and cross-phase modulation

Quasi-phase-matched second-harmonic generation at periodic quadratic susceptibility gratings with self-phase and cross-phase modulation owing to Kerr nonlinearities is investigated. A model of interaction of monochromatic plane travelling waves is considered. The solution assumes a nondepleted pump and results for a numerical computation of second-harmonic conversion efficiency for a highly efficient process are presented. It is shown that for high spatial-frequency gratings the efficiency of second-harmonic generation depends on the reduced detuning and the Kerr-nonlinearity coefficient only. In some cases, if the signs of and are opposite, the Kerr nonlinearity can enhance the second-harmonic conversion efficiency due to the compensation of the phase mismatch attained in the below-half-conversion stage by the reversed phase mismatch in the above-half-conversion stage of the process. The computed maximum conversion efficiencies for various values of and are plotted in a contour map on the - plane.     

ПЛОТНОСТЬ ТОКА В АНОД НЫХ ПЯТНАХ ИСКРОВЫХ РАЗРЯДОВ В ВОЗДУХЕ ПР И АТМОСФЕРНОМ ДАВЛЕН ИИ

annapamyp, . .     

A remark on the decay rate of bound muons

The probability of the decay of a bound -meson is calculated using the theory of weak interactions with an intermediate boson. It is found that this theory, like all the others, cannot explain the experimental maximum atZ=26.

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- K-

- K- . , , , Z=26.

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I wish to acknowledge my indebtedness to Professor V. Votruba for suggesting the problem and for valuable discussions.     

Beitrag zum problem der Exo-Emission von festkörpern

Zusammenfassung Es sind die Versuchsergebnisse des Studiums der Photoerscheinungen bei verschieden bearbeiteten Metallen (Au, Al, Pt) angeführt. Die Metallfolien wurden an der Luft mit UV-Licht bestrahlt und gleichmä\ig erwärmt. Die Ergebnisse wurden vom Gesichtspunkt der neueren Kenntnisse über Adsorption, Katalyse und Oxydation diskutiert. Daraus sind Folgerungen gezogen worden, die in manchen Fällen zu Bedenken über die Klärung der Exo-Emissions-Glow-Kurven zu führen scheinen.

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Au, Al, Pt . , . , . , .

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Ich möchte auch an dieser Stelle meinen besten Dank Frau K. Listoová aussprechen für die mit gro\er Sorgfältigkeit durchgeführten Versuchsreihen und K. Huml für die Hilfe bei der Bearbeitung der Versuchsergebnisse.     

ЗАТУХАНИЕ КОЛЕБАНИЙ ЧАСТИЦ В ОБЩЕМ ПОЛЕ С ПЕРИОДИЧЕСКОЙ СТРУКТУРОЙ I

, , . , . .

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The damping of particle oscillations in a general field with periodic structure I

A liner theory is derived, discussing the dynamics of particles in the region of an equilibrium orbit in a general electromagnetic field, which forms a periodic system. The total particle damping is determined from the Hamiltonian found and from dissipative forces brought out by a classical reaction radiation. Relations for the damping of the synchrotron oscillations are derived from the study of the appropriate phase space.

     

Derivations commuting with abelian gauge actions on lattice systems

Let be an action of a compact abelian groupG on aC*-algebraA, and assume that the fixed-point subalgebraA is an AF-algebra. We show that if is a closed *-derivation onA commuting with , and the restriction of toA generates a one-parameter group of *-automorphisms, then itself is a generator. In particular, the result applies if is an infinite product action ofG on a UHF algebra. Furthermore, if in this situation ₁ and ₂ are two derivations both satisfying the hypotheses on , and ₁ and ₂ have the same restriction toA , then there exists a one-parameter subgroup of the action with generator ₀ such thatD(₁)D(₂)D(₀) is a joint core for the three derivations, and ₂=₁+₀ on this core.     

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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, , . , . , . . .

     

Новый метод измерени я магнитокалорическ ого эффекта у ферромагни тных полупроводнико в

, .     

Band-gap structure of the spectrum of periodic Maxwell operators

We investigate the band-gap structure of some second-order differential operators associated with the propagation of waves in periodic two-component media. Particularly, the operator associated with the Maxwell equations with position-dependent dielectric constant (x),xR ³, is considered. The medium is assumed to consist of two components: the background, where (x) = _b , and the embedded component composed of periodically positioned disjoint cubes, where (x) = _a . We show that the spectrum of the relevant operator has gaps provided some reasonable conditions are imposed on the parameters of the medium. Particularly, we show that one can open up at least one gap in the spectrum at any preassigned point provided that the size of cubesL, the distancel=L betwen them, and the contrast = _b / _a are chosen in such a way thatL ^–2, and quantities ^-1-3/2 and ² are small enough. If these conditions are satisfied, the spectrum is located in a vicinity of widthw(^3/2)^-1 of the set {² L ^-2 k ²:kZ³}. This means, in particular, that any finite number of gaps between the elements of this discrete set can be opened simultaneously, and the corresponding bands of the spectrum can be made arbitrarily narrow. The method developed shows that if the embedded component consists of periodically positioned balls or other domains which cannot pack the space without overlapping, one should expect pseudogaps rather than real gaps in the spectrum.     

Configuration mixing and deviations of magnetic moments from Schmidt lines

Deviations of nuclear magnetic moments of oddA nuclei from the Schmidt lines are explained by configuration mixing. The general results obtained are applied to several nuclei and the magnitudes of the admixture coefficients necessary to explain the deviations are estimated. The results show that the deviations can be successfully explained only for those nuclei, in which possible configuration admixtures give contributions to the magnetic moment linear in the admixture coefficient.

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A . , . , , , .

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This work was done as a diploma thesis at the Faculty of Technical and Nuclear Physics, Technical University, Prague.

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In conclusion I want to thank Dr. L. Trlifaj for suggesting this subject and for his guidance in its realization.     

Zero value of the Schwarzschild mass for an asymptotically Euclidian system of gravitational waves

A class of the asymptotically Euclidian space-times is shown to exist for which the Schwarzschild mass is equal to zero. The coordinate atlases of these space-times satisfy two additional conditions: _k (-gg ^0k )=0 and _ik ⁰ _0g ^ik - _ik ^k _0g ⁰ⁱ =0. In aT-orthogonal metricgs ²=g ₀₀ dt ² -g dx dx these conditions take a simple form: ₀(detg )=0 and (₀ g )(₀ g )=0.     

Nonlinear properties of the laser as an amplifier

Summary The paper presents the results of a theoretical analysis of an optical traveling-wave amplifier, to whose input are applied monochromatic pulses of frequency equal to the transition frequency. At distances zp(c/2) |2N₂–N₁|/ /(N₁–N₂) where p>1, and for <2₀aN₁ all input pulses assume the form of a stationary pulse (see Eq. (33)). The stationary signal intensity, duration and total energy are substantially dependent on the nonresonant loss in the medium, the relaxation time T₂ and the initial inversion population difference N₁. For loss values >2₀aN₁ the input pulses are attenuated.In the amplifier model considered we have assumed the laser medium to have a uniformly broadened line. This enables us to apply the results of the investigation to a ruby laser which satisfies this condition (by excluding low temperatures).The neglect of pumping and the lifetime T₁ is permissible for values of not too close to 2₀aN₁.Izvestiya VUZ. Radiofizika, Vol. 8, No. 5, pp. 899–908, 1965     

More inequalities for critical exponents

A variety of rigorous inequalities for critical exponents is proved. Most notable is the low-temperature Josephson inequalitydv +2 2–. Others are 1 1 +v, 1 1 , 1,d 1 + 1/ (for d),dv, ₃ + (for d), ₄ , and _{2m 2m+2} (form 2). The hypotheses vary; all inequalities are true for the spin-1/2 Ising model with nearest-neighbor ferromagnetic pair interactions.NSF Predoctoral Fellow (1976–1979). Research supported in part by NSF Grant PHY 78-23952.     

Structural Transformations in a Bi2O3 Crystal and in Bi2O3‐Based Solid Solutions in the Temperature Interval 25–750°C

The Raman scattering spectra of isostructural Bi₂O₃ and Bi_1.8Tm_0.2O₃ in the course of heating have been investigated. It is shown that the sequences of structural changes with increase in temperature differ: and ^* , respectively. In the hightemperature region, the structure takes the form of a disordered cube irrespective of the previous history of specimens.     

The quantum theory of the spontaneous magnetization of ferrimagnetics,anti-ferromagnetics and thin films with arbitrary spin at high temperatures

Using Van Vleck's modification of the Heisenberg theory of ferro-magnetism for substances with arbitrary spin per atom, a generalization of the theory is given for the case of ferrimagnetics, anti-ferromagnetics and thin films with an arbitrary number of sub-lattices and with arbitrary spin per atom. The exchange part of the energy operator is formulated by means of rotated spin operators. The theory contains the quantum-mechanical generalization of non-quantum theories given by Néel and later generalized by Yafet and Kittel. It also contains the theory of thin films proposed recently by the author. The magnetization laws are completely analogous to the relations derived from the theory of molecular fields. The constants of the molecular fields are interpreted by means of exchange integrals. For the special case of spin S=1/2the theory agrees with the results of the work of Vlasov and Imuchametov for ferrimagnetics and anti-ferromagnetics and with the author's for thin films.

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,

, , , . . - , . , . , . . S=1/2 .

     

Die durch eine Belastung induzierte amplitudenabhängige innere Reibung bei Fe-Ni Legierungen

Ohne Zusammenfassung

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Fe-Ni ,

     

On the interpretation of infra-red spectra and the lattice dynamics of cubic BaTiO3

The frequencies of normal modes of vibration (for a wave vectork = 0) of cubic BaTiO₃ are calculated. It is shown that the purely ion crystal BaTiO₃ could not be stable and the covalent bonds are therefore calculated by introducing effective charges. It is found that the lowest optical frequency substantially depends on the magnitude of the Coulomb interactions and is much lower than the other optical frequencies. The results are used to interpret the infra-red spectra of BaTiO₃.

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BaTiO₃

( k = 0) BaTiO₃. , iO₃ , , . , , . BaTiO₃.