Studium der Mosaikstruktur von Kristallen

Zusammenfassung Nach einer neuen Methode wurde der Beflexionsbereich von KCl-Kristallen gemessen. Es wird gezeigt, dass sich die Reflexion der Röntgen-strahlen auch an Mosaikblöcken von KCl der Reflexion am vollkommenen, Kristall nach der Theorie von Darwin und Ewald nähert.     

Studium der van der Waals-Kraft im Bereich kleiner Abstände

The theory of Dzyaloshinskii allows us to calculate the van der Waals force acting between two surfaces which are held at a distance of 10⁴ Å and less. This calculation was based on the experimentally determined absorption data of quarz. The deflection of a thin quarz plate which was supported at one end with a vaporized bar has been measured to verify the theoretical results. Within the range of accuracy a fair agreement could be reached.     

Über das Studium der Bildung der F-Zentren in NaCl Mittels der Exoelektronenemission

The kinetics of the coloration of NaCl by X-rays by means of exoelectron emission is studied. It is shown that this method can be used to investigate the relation between the magnitude of the emission current density and the concentration of colour centres. Differences are found between the kinetics of coloration in volume, observed by other authors, and the kinetics of coloration in the surface layer of the crystal.     

Ein Magnetomechanisches Verfahren zum Studium der Kinetik des Magnetisierungsvorganges

Ohne Zusammenfassung

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Der Elektromagnetische Aspekt der Magnetomechanischen Erscheinung in Gleich und im Monoalternant Pulsierenden Magnetfeld

The electromotive tension induced by Barkhausen discontinuities is studied. These Barkhausen discontinuities are excited by periodic mechanical stress in a d-c and a mono-alternating pulse magnetic field.     

Zur Vorsensibilisierung von Manganaktivierten Zinkkadmiumsulfiden durch elektrische Felder und Infrarotstrahlung

The powder phosphor ZnCdS-Mn was used to make a more detailed investigation into memory, which was first described by Destriau in 1958. The effect of a field and infra-red radiation is modified by prior sensitization of the luminophore; this is apparent during further X-ray radiation primarily as a much higher luminescence intensity which later slowly decreases. A comparison of the results of measuring the brightness and charge on an electroluminescence panel permits conclusions to be reached on the actual mechanism. When a field is applied it excites polarization, the field of which does not have a great influence on the effect studied.     

Phasenumwandlung zweiter Art als kritische Erscheinung eines inneren Phasengleichgewichtes

It is demonstrated that the transition in a state with two internal phases is a second order phase transition. The term internal phases means phase-like regions inside the system which are not separated by boundaries in the sense of ordinary phase boundaries, and the dimensions and shape of which as well as their properties as such are object of an equilibrium. In a generalization (quasi phases) a long ranged correlation of alternating or periodical character is considered as a typical element of the low temperature state. Such states can be described thermodynamically with the help of a new pair of variablesQ-η. The transition intoQ-η-T is generally analogous to the critical point of ordinary phase transitions inP-V-T, andη ～(?t)^1/3 andC _p～(?t)^?2/3 with a small constant of proportionality are obtained (t=T-T _u). Using the Pippard-relations in the formV-V _γ=(dT _γ/dP) (S-S _γ) the low temperature behaviour of the entropy and density surface as a function ofP andT near the transition line can be completely described. E.g. the saturation magnetization of a ferromagnetic model is derived proportional to (?t)^1/3. Under the action of a magnetic field the transition will be of first order when the saturation magnetization is achieved, without the outer field being analogous toP orQ. Should only one internal phase differ from the high temperature state we obtain an edge point (x=0 analogous to theμ ₁?x-diagram of solutions) with finite jump inC _p andη～({t). A possible relationship to the BCS- model of the supraconductors is indicated.     

Studium der Abbaugeschwindigkeit der Oberfläche von markierten festen Stoffen zwecks reaktionskinetischer Untersuchungen, 2. Mitt.: Anwendung von mittels Diffusionstechnik hergestellten Trägern

Eine der oft angewandten Möglichkeiten der Markierung fester Träger mit gasförmigen Tracern ist die Diffusionstechnik. Die mit dieser Technik hergestellten Träger wurden zu reaktionskinetischen und analytischen Bestimmungen herangezogen. Im vorliegenden Artikel werden die Grenzen und die Möglichkeiten der Anwendung dieser Träger anhand der in der früheren Mitteilung abgeleiteten allgemeinen Erwägungen theoretisch begründet.     

Zur Deutung der Struktur der Bremsstrahl-Isochromate des Wolframs an der kurzwelligen Grenze

Ohlin's maximum of the tungsten isochromat may well be explained on the basis of the energy bands of tungsten calculated byManning andChodorow. The photons near the threshold voltage are then assumed to arise from transitions of the primary electrons to the unoccupied levels of the 5d and 6s bands. Using this explanation one has to drop, however, a selection rule formulated byNijboer, admitting only transitions to final s states. The validity of this ?s selection rule“ is critically examined. For a strict treatment one has to calculate the matrix elements connected with the transitions, using the exact wave functions of the tungsten crystal. These, however, are not known sufficiently. ThereforeNijboer appliedNedelsky's results for free-free transitions at the isolated atom to the transitions to bound states of the solid. Yet according to calculations made recently byGuggenberer the s selection rule is put into question even for free-free transitions. — A better approximation is obtained considering electron transitions from the continuum to the 5d and 6s states of the isolated atom. A calculation of the corresponding matrix elements is carried out. It shows that both kinds of transitions are of about the same probability at energies around 1 keV which are of special concern to us. Therefore it is allowed to use the 5d band for explaining the tungsten isochromat.     

Energieverlustmessungen an der Legierungsreihe Rhodium-Palladium-Silber

Characteristic energy loss spectra of rhodium, palladium, silver and the intermediate solid solutions Rh₅₀Pd₅₀ and Pd₅₀Ag₅₀ were measured in reflection. The electrons primary energy was variied from 200 to 800 eV. The total scattering angle was 45°. The first energy loss ΔE ₁ was found to be the most prominent. Its value is closely related to the position of the Fermi edge in a rigid band model of this alloy series. A comparison with the shift of the Fermi edge from isochromat spectroscopic measurements shows good agreement of ΔE ₁ with \(\hbar \omega _{\varepsilon _1 = 0} \) . The excitation probabilities of theDE ₁-loss for rhodium and palladium were measured. For primary energiesE}>300 eV they are in good agreement with a formula given byRitchie for surface losses in thick foils. ForE<300eV, the decrease of the probability seems to be a consequence of very small “effective” penetration depths in the concerning metals. TheRitchie formalism for very thin foils can account for our results in this case also. The resulting “effective” penetration depth of about 5 Å forE≈300eV is in good agreement with the magnitude of LEED-measurements.