The diffusion and non-radiative transfer of excitation energy in molecular crystals containing foreign molecules

A study is made of the non-radiative transfer and diffusion of excitation energy in molecular crystals containing foreign molecules and its influence on the luminescent properties of these crystals.

---

,

, .

     

Stationary states of an electron in the field of a hole in an ionic crystal

An approximate solution is given of the Schrödinger equation for S-states of an electron in the field of a hole, when the potential energy of the electron has the form — e²/r [1+exp (–qr].

---

s- , –e²/r [1+exp (–qr].

     

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.

---

ZnS-Cu,

e ZnS-Cu . ZnS-Cu, .

---

---

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.     

On the relation between the thickness dependence of optical absorption and the surface layers of barium titanate single crystals

Single crystals of BaTiO₃, prepared by crystallization in the system BaCl₂-BaO-BaTiO₃-show a dependence of the optical absorption coefficient on the sample thickness. The observed thickness dependence of the absorption coefficient can be explained by the existence of a surface layer with optical properties differing from those of the inner part of the crystal. By means of an etching method a direct determination of the thickness of the surface layer of crystals in the thickness range of 0.075 to 0.178 mm was carried out. The value found is (6.0±0.2)×10^-4 cm.

---

iO₃, 1₂-BaO-BaTiO₃ . . 0,075 0,178 mm. (6,0±0,2). 10^-4 cm.

     

Über den Einfluss von Stickstopf auf die Exoelektronenemission von Germanium

Zusammenfassung Es wurde der Einfluß eines Bombardements mit Stickstoffionen vor der Erregung untersucht und gezeigt, daß die Stiekstoffatome eine große Rolle bei der Entstehung des Emissionsmaximums bei 150° spielen.

---

-

, 150°C.

     

Das Anhaften von Exzitonen an Störstellen des Kristallgitters

Zusammenfassung Es wird der Proze des Anhaftens von Exzitonen an Vakanzen und F-Zentren in den Ionenkristallen studiert. Die Bewegung der Exzitonen im Felde der Vakanz und des F-Zentrums wird in adiabatischer Annäherung untersucht. Mit Hilfe der klassischen Methoden werden die Wirkungsquerschnitte des Anhaftens des Exzitons an den Vakanzen und F-Zentren bestimmt und diskutiert.

---

F- . F- . F- .

     

Spatial period of moving striations as function of electric field strength in glow discharge

During a systematic investigation of the parameters of a moving stratification in a glow discharge in helium and neon it was found that the spatial period of the striations is a simple, unique function of the d-c (constant) component of the longitudinal electric field strengthE. It was found that this dependence is hyperbolic and that the simple relation (1) or (2) thus holds. In the relation has the significance of a potential fall between the corresponding points of two neighbouring striations and in the measured range of pressures, currents and diameters of discharge tubes it depends only on the sort of gas and type of striations.

---

, , E. , , , (1) (2). (1) (2). , .

---

---

The principal results of this work were reported at the 1st conference on electronics in Prague on April 26, 1960.     

Explicit determination of a potential withn bound states by means of the solution of the inverse problem

A potential havingn bound states is obtained for a Jost functionf(k), given as the ratio of two polynomials of the ordern in the impulsek, by solving the Gelfand-Levitan equation. The special case when the parameters have such values that no bound state need be considered, is studied separately. In the cases studied the linear integral Gelfand-Levitan equation is transformed ton linear inhomogeneous algebraic equations forn unknown quantities, by means of which one can determine the potential and the solution of the Schrödinger equation. Forn=1 the results agree with those previously known.

---

f(k), n- k, - , . , , . - , . n=1 .

     

Photo-piezoelectric effect in semiconductors

A new photo-voltaic effect was observed which is caused by inhomogeneous distribution of the pressure in a semiconductor. Its production can be explained by the dependence of the energy gap on the pressure.

---

, . .

     

Über die Natur der Magnetomechanischen Erscheinung im Wechselmagnetfeld

Ohne Zusammenfassung

---

     

The quantum theory of multipole radiation in a dielectric

The potentials of an electromagnetic field of multipoles in a dielectric, which is realized by a dielectric sphere having a perfectly conducting surface, are derived. The diagonal values of the energy for thez component of the angular momentum and the square of the angular momentum of the field are determined and also the ratio between thez component of the angular momentum and the energy and the ratio between the square of the angular momentum and the square of the energy. It is shown that the total angular momentum can be divided in the usual way into orbital and spin parts but that these parts cannot be interpreted as the orbital and spin angular momentum because their eigenvalues cannot be the eigenvalues of any operator of infinitesimal rotation. In the commutation rules of a multipole field the vector character of the field is to a certain extent suppressed and the spin of the photon in a state with a certain value of the energy, parityz component of the angular momentum and the square of the angular momentum is not defined.

---

, . ,z— , , z— . , , , , , - . , ,z— .

---

---

In conclusion the author thanks Dr. . Muziká for directing the work, F. Samek for valuable remarks and discussion and J. Kvasnica for help in preparing the paper for publication and for adding a number of remarks.     

On the problem of a cyclotron for particles with relativistic increase in mass

The paper deals with the problem of circular accelerators with time constant magnetic field and constant frequency of the accelerating voltage. An analysis is made of the possibility of compensating the change in time of revolution (caused by the increase in mass during energy growth) by simultaneous axial and radial displacement of the equilibrium orbit. It is found that the problem can be solved only with certain approximations. The approximate numerical parameters of the accelerator are given and the approximations used are discussed. The paper is based on [1].

---

. ( ) c . , . . [1].

---

---

In conclusion the author thanks the director of the institute Ing. J. Váa for permitting publication and Dr. M. Seidl, Ing. J. Teichman, Ing. R. Klíma and Ing. Z. Sedláek who, apart from solving other problems of the accelerator, cooperated with the author on its very conception.     

Thermostimulierte Exoemission und Lumineszenz von MgO und CaO

Ohne Zusammenfassung

---

MgO CaO

---

Ich danke bestens Frau K. Listoová für die sorgfältige Durchführung der Versuchsreihen und Ing. S. urovi und Dr. A. Bergstein für das liebenswürdige Überlassen der Präparate.     

The distribution of neutron density in the vicinity of a partly inserted black rod in two-group approximation

The neutron density in the vicinity of a black cylindrical rod partly inserted in a bare reactor is calculated and illustrated by a numerical example. The starting point is a two-group diffusion theory approximation. While the dependence of the effect of the rod on the insertion depth can be calculated simply by means of perturbation theory, the question of the neutron density estimate in the vicinity of the rod is considerably more difficult and in some considerations the estimate of the neutron density caused by the presence of the rod is indispensable. The method makes it possible to determine the reactivity value of the rod in dependence on the insertion depth and especially the neutron density deformation in the vicinity of the rod.

---

()

. , . , , . , . [1] . .

---

---

In conclusion the author thanks J. Svato for help in carrying out the numerical calculations.     

On the ferromagnetism of thin films

In this paper the magnetic properties of ferromagnetic thin layers are studied by calculating the partition function for the magnetic system inKirkwood's approximation of the second order. The results obtained for the Curie temperature and the magnetization are in somewhat better agreement with the experiment than those obtained by Valenta.

---

. , , .

---

---

The author extends his thanks to the group of research workers who performed the numerical calculation of the Curie temperatures on the computer CIFA 1, as well as gratitude to Dr. l. Valenta for so kindly supplying information on the results of his investigations on the same subject.     

Zur Abhängigkeit der Wärmeleitzahl von Gasen und Flüssigkeiten vom Druck und von der Temperatur

Ohne Zusammenfassung

---

     

Fundamental concepts of the theory of dislocations

The fundamental concepts of the theory of dislocations are given in an exact way and some theorems are proved.

---

.

---

---

In conclusion the author would like to thank Professor M. Valouch and Professor L. Zachoval for the interest they took in this work and for remarks and advice which helped to improve it.     

Der Zusammenhang der Rechteckigkeit der Hystereseschleife von Mangan-Magnesium-Ferriten mit dem inneren Entmagnetisierungsfaktor

Ohne Zusammenfassung

---

     

Die Integralbeziehungen bei der stationären laminaren Strömung mit geschlossenen Stromlinien in annähernd kreisförmigen Gebieten

Zusammenfassung Für die statioäre lineare ebene Strömung mit geschlossenen Stromlinien bei einer großen Reynoldsschen Zahl in annähernd kreisförmigen Gebieten werden zwei Integralbeziehungen (5) und (9) abgeleitet. Nach der ersten von diesen ist das Integral der Reibungskraft entlang der Grenze des Strömungsgebiets direkt proportional der Länge dieser Grenze und der Größe der Rotation der Geschwindigkeit im Kern der Strömung. Aus der zweiten Beziehung geht hervor: Das Volumen der in der Zeiteinheit den Schnitt der Rezirkulationsgrenzschicht durchfließenden Flüssigkeit ist direkt proportional dem Integral entlang der Gebietsgrenze aus der Differenz der Quadrate der Strömungsgeschwindigkeit an der Grenze des Kerns und der Geschwindigkeit an der Gebietsgrenze und umgekehrt proportional der Größe der Geschwindigkeitsrotation im Kern und der Länge der Gebietsgrenze.

---

(5) (9). . : , , .

     

Die Röntgenolumineszenz von NaCl-Kristallen mit Kobalt

Ohne Zusammenfassung

---

NaCl