Desorptions- und Reaktionskinetik der Erdalkalien Calcium und Strontium mit Chlor an Wolfram. Teil I: Chemisches Gleichgewicht der Oberflächenreaktion M + Cl = MCl im stationären Zustand (M = Ca,Sr)

Desorption- and Reactionkinetics of the Alkaline Earth Elements Calcium and Strontium with Chlorine on a Tungsten Surface — Part I: Chemical Equilibrium of the Surface Reaction M + Cl ? MCl in the Steady State (M = Ca, Br) Utilizing positive and negative surface ionization the reaction M + Cl = MCl (M = Ca, Sr) was studied at a hot tungsten surface under steady state conditions. Comparing the results obtained either by simultaneous M- and Cl₂ -exposures or by MCl₂ -exposure the existence of chemical equilibrium could be confirmed for the reaction in the temperature interval 1600 K.2000 K; at higher temperatures this equilibrium can be disturbed considerably by the desorption of the reacting components. From the experimental results we obtained under conditions of chemical equilibrium the energy of dissociation of MCl-molecules in the gasphase (D = (3.9 ± 0.15) eV, D = (4.2 ± 0.15)eV) and in the case of a strong disturbance of the equilibrium the difference between the activation energies of desorption and of dissociation of MCl-molecules on the surface (? - D? = (1.6 ± 0.2) eV, ? - D? = (1.4 ± 0.2) eV).     

Anvendung und Perspektiven der Strahlungsvernetzung in der Volkswirtschaft der DDR

Zum angegebenen Thema wurde vom Zentralinstitut für Festkörperphysik und Werkstofforschung der Akademie der Wissenschaften der DDR (ZfFW) gemeinsam mit dem Bezirksvorstand Dresden der Kammer der Technik am 9. 10. 1975 ein Tageskolloquium veranstaltet. Es wurden 100 Teil-nehmer registriert, wobci Kombinate und Betriebe zur Anwendung von Plasten und Elasten stark vertreten waren.     

Desorptions- und Reaktionskinetik der Erdalkalien Calcium und Strontium mit Chlor an Wolfram. Part II: Kinetics of the Elementary Steps of the Surface Reaction M + Cl ⇌ MCl (M = Ca,Sr)

Desorption- and Reactionkinetics of the Alkaline Earth Elements Calcium and Strontium with Chlorine on a Tungsten Surface — Part II: Kinetics of the Elementary Steps of the Surface Reaction M + Cl ? MCl (M = Ca, Sr) Utilizing pulsed molecular-beam-technique the kinetics of desorption of Strontium, Calcium, and Chlorine as well as that of the molecules SrCl and CaCl, which are formed at the hot tungsten surface, was investigated. Thereby, the following values were obtained for the activation energies of desorption: ? = (3.76 ± 0.05) eV, ? = (3.32 ± 0.07) eV, ? = (4.16 ± 0.05) eV, ? = (4.2 ± 0.3) eV and ? = (3.9 ± 0.3) eV. Combining these results with the steady-state-results from part I [1] the temperature dependency of the rate constants of dissociation and recombination of MCl-molecules at the tungsten surface could be determined. The values obtained for the dissociation energies D of SrCl and CaCl on tungsten are (0.5 ± 0.5) eV and (0.3 ± 0.5) eV, respectively. The molecules are stabilized on the surface by the activation barrier for dissociation D? only, which was found to be (2.8 ± 0.5) eV for SrCl and (2.3 ± 0.5) eV for CaCl.     

Interferometrische Bestimmung der Gastemperatur in der Stickstoffniederdruckentladung

A Michelson-interferometer in combination with a He-Ne-laser was used to determine the gas temperature in a nitrogen low pressure gas discharge. With this method the radial temperature profile could be measured to about 96% of the tube radius. Moreover rotational temperatures were measured with a 2 m-grating spectrograph from the spectrum of N₂- and N₂⁺-bands. In the range from 4 to 10 torr and 25 to 100 mA gas temperatures between 460 and 890 K were measured with the belonging rotational temperature from 620 to 1170 K. At pressures below 10 torr a difference of the rotational temperatures from the first negative and the second positive system was found. A qualitative consideration on the mechanism of the radial heat conductivity in the positive column was added.     

Zur Definition der Drehimpulseigenfunktionen in der Vektormesontheorie

There are three possibilities for the introduction of angular momentum eigenfunctions in the vector-meson-theory: 1. Multipole fields, 2. orbital angular momentum eigenfunctions, 3. helicity eigenfunctions. We shall define these functions by eigenvalue equations and present their mutual relationship. In analogy to the usual momentum quantization we may quantize the field with respect to each of the three systems of angular momentum eigenfunctions.     

Zur Existenz der Zweierlei Strukturen der Stehenden Schichten in der Niederdruckentladung in Neon

Zusammenfassung Auf Grund der vorgenommenen Messungen läßt sich behaupten, daß die Strahlung beider Schichttypen dem Neon angehört und keineswegs irgendeiner Beimischung eines fremden Gases, das sich im Neon vorfinden könnte. Damit ist jedoch der Einfluß geringer Beimengungen nicht ausgeschlossen, welche unter gewissen Bedingungen trotz der stufenweisen Ionisierung, metastabiler Zustände u. ä. eine wesentliche Rolle bei der Ausgestaltung der Elementarprozesse spielen können und die bei unserer Messung nicht festgestellt wurden.

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Optical spectral analysis is used to investigate the double structure of standing striations in the positive column of a d-c glow discharge in Ne. The course of the relative intensity of the different spectral lines along the axis of the discharge tube is given. It follows from the measurements that the radiation of both types of striations in a double structure corresponds to neon and not to the admixture of a strange gas. The possible influence of this admixture on the formation of a double structure is not, however, excluded.

     

Greensche Funktionen in der Theorie der Kernmaterie

The aim of this article is the representation of the theory of nuclear matter with the technique of many-body Green functions. We have treated the theory of Green functions thoroughly in the first chapters taking support of the functional method, which offers a convenient approach to the construction of the theory. After treatment of the properties of the exact two-point function and of the effective single-particle potential, preconditions and properties of the approximate solutions are discussed. Results achieved todate are treated in chapter 6. Brueckner theory and allied methods are not further discussed, since these are sufficiently known. The theory of linear response, being important for the semi-phenomenological treatment of real atomic nuclei, is presented in appendix A.     

Formfaktoren in der klassischen Dynamik der Teilchen

The classical dynamics of extended particles is considered. The restrictions imposed on the form factors by the Lorentz and gauge invariance as well by causality are shown.