К ВОПРОСУ О ФОТОПРОВО ДИМОСТИ ФОТОГРАФИЧЕСКОЙ ЭМУ ЛьСИИ

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Polarization of photo-luminescence of ZnS: Cu monocrystals

Different models of luminescence centres are discussed on the basis of measurements of the composition of ZnS monocrystal photo-luminescence in different polarizations and temperature dependence of the degree of polarization. Those of the models submitted by Birman, which assume the polarization to be due to the different force of the oscillators for transitions withEc andEc, or models assuming luminescence polarization to be due to the orientation of the luminescence centres, agree with the results of experiments, i.e. the temperature independence of the degree of polarization and the conformable spectral composition of both polarizations. It is also shown that measurements made up to now of the degree of polarization must be taken as orientational as a consequence of the depolarizing influence of the diffused rays of luminescence on its value.

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ZnS: Cu

ZnS , . , . . , , , E E, , . , , - .

     

Der Einfluss der Schlagdeformation auf das Entstehen von Martensit-Plättchen

Ohne Zusammenfassung

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Anticommutative Electric and Magnetic Charges, and the Monopole Question

The monopole question is treated anew in the light of a recent, strictly covariant,extended formulation of fermion quantum field theory naturally including alsoa pseudoscalar variety of conserved charges. The essential novelty lies in theresulting quantum property of anticommutivity between scalar and pseudoscalarcharge varieties, which should in particular apply to electric and magnetic charges.As an immediate outcome, there should no longer be any (Dirac-like) quantizationcondition relating these charges and binding the magnetic elementary charge tohave a very great strength. A generalized Lagrangian approach to the monopoleproblem is made truly viable, leading to two independent local gauge couplingswhich are separately generated by the electric and magnetic elementary chargesand are not allowed to interfere. This would prevent electric and magneticmonopoles from mutually interacting and would particularly account for theabsence of magnetic sources in ordinary electromagnetism. Within such aframework, an electric charge eigenstate with a nonzero eigenvalue is bound tohave a null magnetic charge expectation value, and the magnetic dipole momentof an electrically charged point fermion may actually be seen as resulting fromthe additional internal presence of a single magnetic charge subjected to a maximaluncertainty in sign. An easy estimate makes it allowable to assign to this chargea strength just equal to that of the partner electric charge. Such a conjecture leadsto a dual model of a charged point fermion where the electric and magneticroles can well be interchanged with no observable effects. In the associatedformalism, duality symmetry is already included without the need to appeal toany missing electromagnetic phenomenology to be discovered.     

Form of the NH3 spectral lines in the impact approximation and analytical expressions for the relaxation parameters

The half-width and cross-relaxation parameter are calculated for a series of rotational transitions on the basis of a rigorous theory taking account of the correlational broadening of the doublet components. The absorption of the doublet lines of the transition J = 4 5 for the system NH₃-N₂ and the transition J = 5 6 for NH₃-NH₃ is analyzed. For the vibrational ground state, analytical expressions are given for the parameters and .Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 3–7, June, 1984.     

The electroluminescence op ZnS-Cu single crystals excited with pulses of alternating polarity

The brightness waves of electroluminescence of ZnS—Cu were measured for the case of excitation with rectangular pulses as a function of the amplitude of the pulses and the temperature. A concrete model is proposed for electronic processes in barriers in ZnS crystals, the consequences of which for the decay of electroluminescence are in agreement with measurements.

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ZnS-Cu,

e ZnS-Cu . ZnS-Cu, .

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In conclusion the author thanks M. Trlifaj for valuable remarks and discussions, Z. Vojta and E. Rechziegel for constructing an important part of the apparatus and F. Karel for the electroluminescent crystals.     

Hydrodynamic Limit of Brownian Particles Interacting with Short- and Long-Range Forces

We investigate the time evolution of a model system of interacting particles moving in a d-dimensional torus. The microscopic dynamics is first order in time with velocities set equal to the negative gradient of a potential energy term plus independent Brownian motions: is the sum of pair potentials, V(r)+ ^d J(r); the second term has the form of a Kac potential with inverse range . Using diffusive hydrodynamic scaling (spatial scale ^–1, temporal scale ^–2) we obtain, in the limit 0, a diffusive-type integrodifferential equation describing the time evolution of the macroscopic density profile.     

On the yellow colouring of lithium fluoride crystals

The paper deals with the causes of the yellow colouring of LiF crystals. In accordance with some other writers the authors arrived at the conclusion that colouring is caused by impurities. Selective absorption in the infra-red region at 2·8 is independent of this colouring. Analytical data were supplemented by crystal growing experiments in which defined admixtures of heavy metals, such as Co, Mn, Fe, Cr, Ni, Pt, Cu, were added to the melt. It is shown that, of the admixtures used, the most intense colouring is produced by manganese. Experiments on the effect of Cu and Pt were not entirely conclusive. In vacuum colour-producing impurities evaporate quite easily from the melt until their concentration drops below the critical limit required for colouring; in air this happens only if the charge is left in the melted state for a longer period (in our case a 1 kg charge was kept at 100°C above melting point for 36 hours). Results are improved if a dried gas, for instance nitrogen, is bubbled through the meit. A colourless crystal can be obtained in this manner even without using a vacuum; the starting material, however, must be sufficiently pure. A new method was worked out for preparing the salt by direct precipitation of LiCl and HF. Heavy metals are removed from the lithium component by means of cupral and dithizone. The construction of the apparatus used for the crystal growing experients in vacuum differs from that described in the appropriate literature.

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LiF

LiF. , . 2,8 . . , , , Mn, Fe, Cr, Ni, Pt, Cu. , . , . Pt . , , , ( : 1 kg-36 100° ). , , , . , , . LiCl HF. . , .

     

The effect of oxygen on the electric conductivity of a cuprous oxide single crystal

The effect of an excess of oxygen on the electric conductivity of a pre-illuminated and heated single crystal of Cu₂O is investigated. It is found that the influence of illumination on the electric conductivity, together with the concentration of impurities, increases with increasing oxygen pressure during annealing.

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, Cu₂O. , .

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In conclusion the author thanks E. Klier and J. Pastrak for valuable remarks and discussion.     

The use of the kramers-kronig relations in determining optical constants

The paper discusses some of the ways in which to avoid difficulties in applying dispersion relations to experimental data of the optical constants of solids, particularly with regard to measurements in a narrow frequency range.

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The rotation of bloch walls

A Bloch wall has an integral magnetic moment which is due to the spatial distribution of the magnetic moments of the spin. The external magnetic field thus acts on the wall with a torque, which leads to the rotation of the sub-domains and therefore to deformation of the walls. A theory of this rotation is given and from it a microphysical model of the undulatory surface structure in uniaxial ferromagnets is derived. Experiments performed on magnetoplumbite single crystals fully confirm the theoretical assumptions.

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Our thanks go to J. Fousek and Z. Málek who by reading this paper contributed greatly to the clarity of its presentation.     

The influence of elastic deformation on the magnetostriction constant of nickel and iron-nickel alloys

The dependence of the magnetostriction constant of different materials in the form of a wire on the elastic elongation was measured. With pure nickel the magnetostriction constant is independent of the elastic deformation. All three alloys of iron and nickel and the triple alloy Fe-Ni-Co exhibit a linear dependence on the deformation, which differs for different crystallographic texture. In two iron-nickel alloys the dependence of the magnetostriction constants of the single crystal on the elastic deformation was calculated from measurements on polycrystals having different crystallographic textures. In the triple alloy Fe-Ni -Co a considerable linear decrease in the volume magnetostriction with the elastic elongation was also found. The observed changes can be explained by assuming the influence of the lattice deformation on the spinorbital interaction in alloys.

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. . - Fe-Ni-Co , . - . , Fe-Ni-Co . - .

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A preliminary report on some of the results of this paper was given at the conference on magnetism in Kyoto (Japan) in September 1961.

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In conclusion the authors thank Z. Frait C. Sc. and S. Libovický for remarks, J. Míová for help in the measurements, members of the chemical department of our institute for annealing and analyzing the samples and members of the Metal Research Institute in Panenské Beany for their exceptional helpfulness in preparing the wires.     

Single crystal diffraction pattern of germanium

The diffraction pattern for the (111)-reflection of germanium was measured by means of the three-crystal arrangement and compared with dynamical theory. The results obtained indicate the possibility of using germanium crystals for precise measurements in X-ray spectroscopy.

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(111) . .

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In conclusion the authors thank Ing. Hrubý for preparing the germanium single crystals and participating in the preparation of the surfaces; they are also indebted to V. Smutná, R. ída and A. Irra for the care with which they carried out various tasks and V. Horáková for carefully performing the numerical calculations.     

О ЗАТУХАНИИ ФАЗОВЫХ К ОЛЕБАНИЙ В СИНХРОТРОНЕ СО СЛАБ ОЙ ФОКУСИРОВКОЙ

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On the damping of phase oscillations in a weak-focusing synchroton

An equation of the phase oscillations in a weak-focusing synchroton is derived for the case that an arbitrary high-frequency field of sinusoidal time dependence is distributed on the circumference of the accelerator. It is shown that the damping of phase oscillations is practically independent of the shape of the high-frequency field. From this we get the special case that any adjustments to the accelerator gaps, considered for example in [1], are useless.

     

Усовершенствование рентгенометрическо го метода определения дефекто в решетки третьего ро да в поликристаллическ их и порошкообразных материалах

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The propagation of excitation energy in perturbed crystals

The process of the propagation of excitation energy in perturbed dielectric crystals with a weak bond between the atoms having zero permanent dipole moment is studied. It is shown that on certain assumptions this process of propagation can be regarded as the motion of a Frenkel exciton in the electrostatic field of the defect. Frenkel's exciton can be characterized in this case as a neutral polarizable particle having induced dipole moment equal to the change in the induced dipole moment of the crystal during the excitation of one of its atoms.

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Die Exoelektronen- und Thermoelektronenemission bei einigen Halogeniden

Zusammenfassung Es wird Vergleich angestellt zwischen den experimentellen und theoretischen Thermoemissionskurven für den mono- und bimolekularen Proze bei Kristallen von NaCl und CaF₂, die die Farbzentren F enthalten. Rechnerisch wird der Einflu der Austrittsarbeit auf die Lage der Thermoemissionsmaxima und auf die Intensität der Thermoemission verfolgt. Die bei den Halogeniden erzielten Ergebnisse gaben die Möglichkeit, gewisse Schlüsse zu ziehen über den Mechanismus der Thermoelektronenemission bei Oxydkathoden.

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- NaCl u CaF₂, F. . , .

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Wir danken unseren Kollegen, insbesondere dem Kandidaten der phys. math. Wissenschaften J. Kanturek für die wertvollen Diskussionen und K. Listoová für die sorgfältige Durchführung der Versuche.     

Change in primary extinction of X-rays in solid solution of NaCl-CdCl2

The Suzuki model of regions with a hyperstructure was verified, the dependence of their size on the cooling rate was found and it was determined that they disappear at temperatures between 250° and 300°C according to their composition. Up to 1000 Å their structure is coherent with a matrix lattice and their formation is not accompanied by a decrease in the primary extinction. Regions above 1000 Å are partially incoherent and their formation and disappearance are apparent by a change in the primary extinction.

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NaCl-CdCl₂

, , , 250°–300°C . , 1000 Å, . , 1000 Å, .

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The author would like to thank I. Kunzlová, and M. Lébl for preparing the crystals of NaCl-CdCl₂ solid solution and Dr. Trnka for determining the cadmium Concentration in them.     

ВЛИЯНИЕ ПАРНЫХ СИЛ НА ЭНЕРГИЮ ГИГАНТСКОГО РЕЗОНАНСА

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Influence of pair forces on the giant resonance energy

The influence of various nucleon-nucleon forces on the giant resonance energy is investigated with the help of the sum rules. The dependence of the contribution of exchange forces to the integral cross-section of the gamma quantum absorption on the number of protons and neutrons is obtained for light nuclei.

     

The theory of the spinning impact of imperfectly elastic bodies

The first theoretical solution is given of the spinning impact of an imperfectly elastic sphere on a rigid, imperfectly rough plane. The method of solution is based on the general static theory of the impact of rough bodies, elaborated by one of the authors in 1952 [5]. The problem leads to a non-linear differential equation, which can be solved only by an approximate numerical method. The results of the theory are in good agreement with the experiments carried out in 1947 [4].

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, . , 1952 . , . .

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In conclusion the authors thank Dr. Vaclav Goldbach, lecturer at our department, for valuable help in making the experimental apparatus and in carrying out the difficult measurements by the method described in section 3 of this paper. Our thanks also go to O. Brha for help in the graphical solution and drawing of the figures.