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.

---

-

, , . , . , . . .

     

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

Ohne Zusammenfassung

---

Fe-Ni ,

     

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.

---

- K-

- K- . , , , Z=26.

---

---

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

Magnetic anisotropy in thin ferromagnetic films

The magnetic properties of thin ferromagnetic films are studied taking into account the magnetic anisotropy term in the Hamiltonian. In the second approximation equations are obtained for the magnetization of the monatomic layers parallel to the surface of the thin film. From these equations one obtains the Curie temperature, which depends on the thickness of the thin film and the ratio a between the anisotropy constant and the exchange energy between two neighbours. A value can be chosen for such that the thin film becomes ferromagnetic only for a thickness greater than a definite value and in this manner the theoretical results can be fitted to the experimental data. The situation in cobalt thin films is dealt with in particular.

---

. , . , . , , - , . , , .

---

---

The author extends his thanks to the research workers of CIFA 1 as well as to Dr. L. Valenta for information on the same subject.     

The elastic coupling between longitudinal and transversal vibrations of isotropic rods I. Rods of square and rectangular cross-section

A new approximate method for theoretically calculating longitudinal vibration frequencies of isotropic homogeneous rods of square and rectangular cross-section is given. We divide a three-dimensional longitudinal vibration into three one-dimensional ones; the coupling between the principal strains in question is assumed to be linear, similarly as in the static case of simple tension. The coupling between the deformations is realized by variable coupling parameters or depending on the order of vibrations (contrary to Rayleigh's correction where Poisson's ratio is the coupling parameter). These parameters are defined by the condition that the corresponding frequency must be minimized (stationary).Up till now Giebe and Blechschmidt [2] have given the best approximate method of calculation. The series of their calculated frequencies corresponds to the measuredones nearly as well as the frequencies calculated by us. The theory described here, however, contains a richer spectrum of frequencies and at the same time explains the frequencies measured in the range of the so-called dead zone, which is the weak point of Giebe's and Blechschmidt's theory.

---

I.

. ; , . , ( , ). , ( ). [2]. , , . , , , , . . , .

     

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.

---

BaTiO₃

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

     

Arbeitstagung über die Physik und Chemie der Kristallphosphore in Berlin

Ohne Zusammenfassung

---

     

The influence of magnetic after-effect on the rectangularity of the hysteresis loop of MgMn ferrites

The influence of the magnetic after-effect on the rectangularity of the hysteresis loop of MgMn ferrites in two different compositions was studied; it was found that this influence is so small that it cannot be the actual cause of a rectangular hysteresis loop of such materials.

---

-

- . , , .

     

On the electroluminescence of ZnS at low voltages

The possibility of explaining non-zero electroluminescence brightness below the minimum ionization voltage by the influence of thermal velocities of electrons is pointed out; the derived voltage dependence of electroluminescence brightness agrees with the measurements in [1].

---

ZnS

; [1].

     

A possible test of quantum electrodynamics by means of polarization effects in electron-nucleon scattering

The differential cross-section is given for the electromagnetic scattering of polarized relativistic electrons on polarized nucleons. The finite size of each particle is taken into account by means of two form-factors. The effect of the possible non-punctiform structure of the electron on the polarization effects in scattering is discussed. It is shown that the internal structure of the anomalous magnetic moment of the electron would show itself in the cross-section by terms depending on the transversal polarization of the incident electrons.

---

. . . , , .

---

---

Summary of results of a diploma-thesis for the degree of graduate physicist.

---

In conclusion the author wishes to express his sincere gratitude to prof. V. Votruba and J. Kvasnica for suggesting this problem, for helpful discussions and valuable advice.     

ЗАТУХАНИЕ КОЛЕБАНИЙ ЧАСТИЦ В ОБЩЕМ ПОЛЕ С ПЕРИОДИЧЕСКОЙ СТРУКТУРОЙ I

, , . , . .

---

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.

     

A contribution to the semi-focusing method with a flat polycrystalline sample

Condition are derived for the approximate focusing of diffraction lines in the chosen, relatively wide angular region, using the semi-focusing method with a flat sample, if a bent crystal monochromator is employed. The form of the absorption factor for a flat polycrystalline sample is derived for the case of uniform oscillation of the sample in the angular region ± around the axis of the camera.

---

, . ± , .

     

On the basic laws of reaction kinetics

The paper gives the basic laws necessary and in principle sufficient for constructing a system of differential equations for any reaction kinetic process. A new and more exact formulation of two of the basic laws (the principle of superposition of partial reaction velocities and the Guldberg-Waage law) is made possible by an exact definition of the important quantities of this subject. In conclusion the paper points out the difference between the general form of the differential equations for concentrations of components expressed in moles per unit weight and that for concentrations of components expressed in moles per unit volume.

---

, . ( ) . , , , .

     

RÄumliche Darstellung der Atomverteilung im Kristallgitter aus einer beschrÄnkten Anzahl von Röntgendiffraktionsdaten

Zusammenfassung Aus den Projektionen der Elektronendichten in drei voneinander unabhÄngigen kristallographischen Ebenen wird die Funktion (2) zusammengesetzt, die das übliche Darstellungsverfahren mit Hilfe der dreidimensionalen Fourierreihe ersetzt.

---

(2), .

     

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.

---

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

     

Bemerkung zur Arbeit von L. ?pa?er: Die Struktur der Oberfl?chlichen Abschlussbereiche in den (100) Ebenen in Eisen [4]

Ohne Zusammenfassung

---

L. paek (100)

     

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.

---

,

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

     

Bemerkung zum Problem der Chemoemission aus Kupfer

Zusammenfassung Es ist offensichtlich, daß das Entstehen eines Emissionsmaximums bei der Rekristallisation durch Oxydationsvorgänge bedingt ist, die gleichzeitig verlaufen, und daß die Rekristallisation das Einsetzen der Emission bloß erleichtert. Als Beweis hierfür dient die Tatsache, daß es unter sonst gleichen Bedingungen bei der Rekristallisation im reduzierenden Medium zu keinerlei Emission kommt. Aus der Messung der Emission bei der Reduktion läßt sich schließen, daß es bei der Ausbildung der Bedingungen für die Emission zu einer Lokalisierung von Elektronen in seichten Elektronenzuständen kommt, wovon die beschriebene Beobachtung der Photoemission zeugt. Wahrscheinlich ist, daß es sich im Falle der Reduktion um eine Exoelektronenemission handelt.

---

     

Der Einfluss von Beimengungen auf die Fasersubstruktur von Zink-Einkristallen

Zusammenfassung An Einkristallen von Zn mit Beimengungen von Cd oder Cu wurde experimentell die Abhä agigkeit der Größe des Durchmessers der Fasersubstruktur vom Gehalt der Beimengungen untersucht, die aus der Theorie von Rutter und Chalmers [1] hervorgeht. Es wird die Möglichkeit gezeigt, die Größe des Verteilungskoeffizientenk aus den erzielten Ergebnissen abzuschätzen.

---

, . , k.

     

Studium der photodielektrischen Erscheinung an lumineszierenden Zinkkadmiumsulfiden

Zusammenfassung Die spektrale Abhägigkeit der photodielektrischen Eigenschaften der lumineszierenden Zinkkadmiumsulfide verschiedener Zusammensetzung zeigt, da eine Beimengung von Kupfer das Eintreten von Zuständen mit groer Polarisierbarkeit hervorruft, die eine Änderung der realen Komponente der Dielektrizitätskonstanten zur Folge haben. Die Kupferkonzentration kann dabei so gering sein, da sie in der Lumineszenzemission gar nicht zur Geltung kommt. Die Infrarotmaxima der Verluste entsprechen Niveaus, die von anderen Autoren und mit anderen Methoden festgestellt wurden. Das Maximum des Exzitationsspektrums im Bereiche des Ausläufers der Absorptionskante hängt mit dem Maximum der Änderung der realen Komponente der Dielektrizitätskonstante zusammen.

---

-

- , , . , . , . .

---

---

Nunmehr im Physikalischen Institut der Karlsuniversität, Prag.