bluuebunny/crossref_metadata_2025 huggingface dataset:
Refractive Index Measurements of Molten Salts with Wave-front-shearing Interferometry
Authors: Wendelöv Lennart W. , Wallin Lars-Erik , Gustafsson Silas E.
Published: March 2015

A wave-front-shearing interferometer has been used for refractive index measurements on liquids.

A test series on water gave agreement within ±5 · 10 -5 with earlier data. The refractive index of molten potassium nitrate has been measured between 340 and 460°C and found to depend linearly on temperature according to the equation

n=1.46478-1.579 · 10-4 · t

at a wavelength of 6330 Å.
On the Lattice-cell-volume Dependence in the Calculation of the Two-point Function in Quantum Mechanics by the Method of Functional Integration
Authors: Hoffmann M.
Published: March 2015

It is shown that the transition from lattice space, where the two-point functions were calculated by means of functional integration, to continuous space Ɛ → 0, which requires in field theories some kind of renormalization, is practicable in quantum mechanics after reordering of series without renormalization. An ambiguity, which occurs, is discussed.
Protonenspinrelaxation in kristallinem Benzol
Authors: Haeberlen U. , Maier G.
Published: March 2015

Für kristallines Benzol wird nach der halbklassischen Methode die Spingitterrelazationszeit T1 und - für zwei Grenzfälle - auch das 2. Moment 〈Δ ω2〉 berechnet. Erstmals werden auch die intermolekularen Wechselwirkungen quantitativ (mit Hilfe einer elektronischen Rechenmaschine) berücksichtigt. Die berechneten Verhältnisse T1 intra/T1 inter und 〈Δ ω2〉 intra/〈Δ ω2〉inter werden mit entsprechenden Messungen von ANDERSON 1 und von ANDREW 2, die berechneten T1-Werte selbst mit eigenen impulstechnischen Messungen bei 5 Frequenzen zwischen 22 und 88 MHz verglichen. In allen Fällen wurde Übereinstimmung zwischen Rechnung und Messung innerhalb der Fehlergrenzen gefunden. Die gemessene Frequenzabhängigkeit von T1 zeigt, daß sich die Molekülbewegung - sprunghafte Drehungen um die sechszählige Symmetrieachse - durch eine einzige Korrelationszeit charakterisieren läßt.
Der zeitliche Anstieg des Stromes in die anomale Glimmentladung
Authors: Schlumbohm Hans
Published: March 2015

Measurements of the current rise of a low pressure discharge in H2 and O2 at p d < 5 Torr·cm under homogenous field conditions have shown that a direct transition from the Townsend- into the anomalous glow-discharge takes place without any change of the voltage across the gap. The current growth is explained by the space-charge-induced variations of the electric field on the gas amplification ead and on the secondary ionisation coefficient γ. At small current densities the space charge causes an increase of the coefficient μ=γ(ead-1) by its influence on γ whereas at higher current densities this initial increase is reduced by a decrease of ead. The current growth rate is calculated using an approximate equation connecting the relative rise d ln J/dt and μ and is in agreement with the experimental values.

At a certain current density the space charge influence on the secondary ionisation and on the gas amplification balance each other and the steady-state condition μ=1 is again fulfilled. The current growth thus ends in a steady anomalous glow discharge state which is determined by both the voltage across the gap and the current density corresponding to μ=1.
Antisymmetrische Feldquantisierung und funktionale Integration
Authors: Klein O.
Published: March 2015

Ausgehend von der von MATTHEWS und SALAM angegebenen Behandlung der antisymmetrischen Quantisierung eines DIRAC-Feldes mittels funktionaler Integration unter Anwendung von antikom· mutierenden Feldfunktionen wird zu zeigen versucht, daß ein widerspruchsfreies Verfahren die Kommutierbarkeit der Feldfunktionen verlangen dürfte.
Zusammenhang zwischen dem Kerr-Effekt und der Beeinflussung der optischen Absorption von Molekülen durch ein äußeres elektrisches Feld: Partieller Beitrag einer Absorptionsbande zum KERR-Effekt
Authors: Kuball H.-G.
Published: March 2015

Zwei senkrecht zueinander polarisierte Lichtstrahlen besitzen nach Durchdringen einer Flüssigkeit oder Lösung, die sich im elektrostatischen Feld befindet, eine komplexe Phasendifferenz, aus der sich Beziehungen zwischen dem KERR-Effekt und der Beeinflussung der Absorption durch ein äußeres elektrisches Feld (Elektrodichroismus) ergeben, die den KRAMERS—KRONIG-Relationen entsprechen. Eine geeignete Zerlegung der Integraltransformation erlaubt die Berechnung des partiellen Beitrags einer Absorptionsbande zum KERR-Effekt aus dem Elektrodichroismus. Für zwei Azamerocyanine wird aus dem experimentell bestimmten Elektrodichroismus die Dispersion der KERR-Konstanten innerhalb einer Absorptionsbande berechnet, die mit der gemessenen Dispersion übereinstimmt.
Die Elektronenanregungsspektren der Phenanthroline
Authors: Perkampus H.-H. , Knop J.V. , Knop A. , Kassebeer G.
Published: March 2015

Zur Deutung der Elektronenanregungsspektren der 10 isomeren Phenanthroline wurden SCF-CI-Berechnungen mit 30 Konfigurationen durchgeführt. Es zeigt sich, daß Lage, Intensität und Polarisation der Elektronenübergänge mit Hilfe dieser Methode sehr gut wiedergegeben werden. Damit erweist sich die SCF-CI-Methode auch äußerst leistungsfähig bei der Beschreibung der Wechselwirkung zweier Hetero-Atome in einem π-Elektronensystem. Die verschiedenen Möglichkeiten der Stellung der Heteroatome zueinander werden durch das Modell richtig wiedergegeben.
π-Elektronendichte und Lage der Protonensignale in den NMR-Spektren der Phenanthroline
Authors: Perkampus H.-H.
Published: March 2015

Die Lage der Protonensignale in den NMR-Spektren der 10 isomeren Phenanthroline wird mit den π-Elektronendichten der C-Atome, an die die Wasserstoffe gebunden sind, verglichen. Für die ungestörten Protonen ergibt sich zwischen beiden Größen eine lineare Abhängigkeit. Abweichungen können durch den Störeffekt des freien Elektronenpaares am Ringstickstoff und Überlagerungseffekte für die 4- und 5-Stellung erklärt werden.
Das Absorptionsspektrum von NaNO3 von 450 — 5700 cm-1
Authors: Matossi F. , Hohler V.
Published: March 2015

The transmittance of single crystals of NaNO3 is observed with grating spectrographs (resolution 1-2 cm-1) in the region from 450 to 5700 cm-1 in polarized radiation. The spectrum is interpreted according to the selection rules of D3d in terms of combination frequencies. Te main absorption maxima of the internal fundamental vibrations are observed at 729 (Eu), 839 (A2u), 1373 (Eu, powdered sample in KI). At 813 cm-1, the A2u fundamental of N15O3 is observed. No lowfrequency libration could be determined for NaNO3; in calcite, however, it was found to be at ω6=20 cm-1.
Untersuchung über die Ausbreitung von elektromagnetischen Wellen in einem zylindrischen Plasma mit Magnetfeld
Authors: Weinhardt Karl
Published: March 2015

Propagation of circularly symmetric electromagnetic modes parallel to the magnetic field lines in the positive column of an argon hollow-cathode arc discharge has been studied. The applied frequency (3·109 cps) was less than both the electron gyrofrequency and the electron plasma frequency. These measurements were compared with dispersion relations for circulary symmetric modes calculated by using the complete MAXWELL equations, the ε-tensor for a cold collisionless plasma, and suitable boundary conditions. It could be shown that the mode which was excited was most likely determined by the boundary of the coupling system and not by the boundary of the whole vessel as originally expected.
Beugung langsamer Elektronen an kugelförmigen oxydierten Kupfer-Einkristallen
Authors: Berndt W.
Published: March 2015

The surfaces of spherical copper monocrystals were investigated with slow electron diffraction. The crystals were grown in the UHV of the diffraction apparatus by cooling-down molten droplets of the metal according to MENZEL'S method. By turning the crystal the diffraction pattern of an arbitrary crystallographic pole may be observed some minutes after crystal growth. On the untreated crystal only the interferences of the copper lattice appear. The patterns have the character of space lattice diffraction if the incident beam strikes a larger spherical calotte of the surface (focussing on the fluorescence screen). If the beam is focussed on the crystal surface (diameter 0.3 mm) the spots on the screen are enlarged and weaker, but the diffraction resembles more the usual two-dimensional type. These facts are explained by taking account of the shape transform of the irradiated spherical surface region. — By heating the crystal flat regions may be produced to some extent at low index poles, giving sharp diffraction spots surrounded by diffuse halos. — The main subject of this work is the study of structure produced by weak oxidation (10-4 Torr O2, 150°C, 30 min.). A c (2 x 2) superstructure developer at the (001)-pole, a c (2 x 6) structure at the (110)-pole. The most remarkable effect of oxygen chemisorption is a very pronounced facetting of the surface: In the neighbourhood of (001) the surface is built up by four macroscopic facets of the type {410}, showing no superstructure. Other types of facetting appear near the (011) - and (111)-pole; in the surrounding of the latter facets of the type {011} appear. — Reduction with hydrogen produces firstly {113} facets near the (001) -pole. After complete reduction this pole is transformed again to a small flat region surrounded by a spherical surface without any facets.
Fluctuation Theory of Irreversible Processes
Authors: Schneeweiss Ch.
Published: March 2015

LANGEVIN equations of the type dn× (t)/dtn+...+c × (t)=K (t) constitute the starting point of a phenomenological fluctuation theory of irreversible processes. These equations are not constructed from transport equations (as in the older theory), but via a generalized MASTER equation from phase space mechanics. The MARKOFF processes of first and higher order defined by the various LANGEVIN equations are studied by the prediction theory of stationary stochastic processes. Instead of the variation principle of the ONSAGEB–MACHLUP theory one has the minimization of the prediction error. The mean relaxation path and the entropy of the considered processes are calculated. It is shown that the entropy consists of one part which is given by the relaxation path and another which is determined by the prediction error.
Effects of Magnetic Shear on Density Gradient Drift Instabilities
Authors: Kitao Kazuo
Published: March 2015

The amounts of magnetic shear necessary to stabilize density gradient drift instabilities are estimated for a plasma with 1≫ β > m/M where β=plasma pressure/magnetic pressure, m and M are the electron and ion masses. The stability criteria for electrostatic convective modes are shown to he slightly modified from those obtained previously for β < m/M. For β > m/M however, we must also consider unstable ALFVÉN type modes. It is shown that the critical amount of magnetic shear is proportional to β-1 for the convective ALFVÉN type modes and to √β for the non-convective modes.
Spektroskopische Bestimmung der Dissoziationsenergie des C2-Moleküls aus den 3IIg -Termen
Authors: Messerle G. , Kkauss L.
Published: March 2015

By means of a new vibration formula of BRODERSEN, taking account of observed vibrational perturbations, the dissociation limit of the 3IIg states of C2 has been determined. In order to do this, some further SWAN bands (A3IIg—X′3IIu) and five high pressure bands (v′=6) have been analyzed. The extrapolations of vibrational levels of the A3IIg and B3IIg states lead to dissociation energies D0 (C2) = 6,07 eV and 6,09 eV, respectively, in good agreement with values obtained by other methods.
Zur Protonenrelaxation von Wasser an Silikagelen
Authors: Michel D.
Published: March 2015

In most cases the proton relaxation of adsorbed liquids and gases is caused by the proton-proton dipolar interaction and the coupling between protons and paramagnetic impurities (e. g. Fe3+-ions) of the adsorbent. The latter relaxation mechanism, however, has been neglected up till now although in some commercial silica gels it’s contribution can be the most important one (see Section 2.2). Consequently, motional phenomena of adsorbed molecules can only be studied by NMR techniques if the relative largeness of these two relaxation rates has been estimated, as can be done by investigating the dependence of proton relaxation-times on the H/D-ratio. Relaxation-time measurements in the temperature range from —100° to +80°C indicate that proton transfers occur between surface hydroxils and adsorbed particles. In a sample of 3/4 statistical monolayer the presence of two different types of water, clusters containing 95% of the adsorbed molecules with correlation time τc2=2.7 · 10-10 s (0°C), and more individually adsorbed particles with τc1 ⪆ 2.3 ·10-8 (0°C), has been inferred (see Section 2.1).
Phänomenologische Koeffizienten für Elektrizitätsleitung und Diffusion in konzentrierten Elektrolytlösungen
Authors: Haase R. , Richter J.
Published: March 2015

Bei Lösungen eines Elektrolyten mit zwei Ionenarten lassen sich aus gemessenen Werten der spezifischen Leitfähigkeit, der Überführungszahlen, des Diffusionskoeffizienten und des Aktivitätskoeffizienten die drei phänomenologischen Koeffizienten L + +, L - - und L + - ableiten, die für Elektrizitätsleitung und Diffusion grundlegend sind. Es wird zunächst gezeigt, wie man die Formeln ohne Beschränkung hinsichtlich des Dissoziationsgrades des Elektrolyten gewinnt. Sodann werden die experimentellen Daten und ihre Herkunft angegeben, wobei möglichst weitgehend auf eigene Messungen zurückgegriffen wird. Schließlich werden die phänomenologischen Koeffizienten in Abhängigkeit von der Elektrolytkonzentration betrachtet. Es handelt sich dabei um wäßrige Lösungen von HCl, HClO4, HNO3, NaCl, CaCl2 und LaCl3 bei 25°C. Der untersuchte Konzentrationsbereich ist sehr groß. Bei CaCl2 werden auch übersättigte Lösungen herangezogen. Der Konzentrationsverlauf von L+
+, L - - und L+ - ist kompliziert. Bei HClO4 wird L+ - im Gebiet zwischen 0,8 und 5 mol · l -1 sogar negativ.
On the Calculation of F-center Wave Functions
Authors: Löffler Alf
Published: March 2015

On the basis of a microscopic theory the ground state wave function of a F-center electron is calculated. In Sect. 1 we derive a HAMILTON operator regarding polarization effects and the distortion of the lattice. In Sect. 2 the wave function for the ground state is calculated assuming the lattice at absolute zero temperature. In Sect. 3 we describe the dependence of the wave function on the lattice oscillations. Numerical results are given in Sect. 4. We found for the ground state of the F-center a similarity law as supposed by experiments. In the appendices we give some details on regarding polarization effects.
On the Field Theoretic Functional Calculus for the Anharmonic Oscillator. II
Authors: Schuler W. , Stumpf H.
Published: March 2015

The theory of solution for quantum field functional equations is developed for a suitable testproblem of quantum mechanics. In Sect. 1 the anharmonic oscillator is described in a field theoretic fashion. In Sect. 2 its functional equations are derived and in Sect. 3 these equations are symmetrized due to physical conditions. In Sect. 4, 5 the expansion of the physical functionals into series of base functionals is discussed and a convenient notation for the operator representation is introduced. In Sect. 6 the representation of the functional equation for an expansion into Dyson base functionals is given. In Sect. 7 and 8 functionals are approximated by expansions with only a finite number of terms and the resulting equations are prepared for integration. In Sect. 9, 10 the integration of the resulting equations for N = 2 and N = 4 is discussed in detail so that one finally obtains eigenvalue equations which contain only integrals to be solved. In the appendices technical details are derived.
Equilibrium and Stability of Normal and Superconducting Current Loops
Authors: Rebhan E. , Salat A.
Published: March 2015

The conditions for equilibrium and stability of a normal or a superconducting current loop in the magnetic field of other fixed loops are derived from the energy principle, both with and without a gravitational field. While loops with finite resistance cannot be levitated, stable equilibrium arrangements of superconductors can be found. In this connection a sufficient criterion for the indefiniteness of homogeneous multilinear forms

Σ Tk1...kn Xk1...Xkn was derived and applied. k1...kn.
Kernquadrupolresonanzspektroskopische Untersuchungen an Chloracetylenen des Typs (CH3)3X — C≡C — Cl (X=C, Si, Ge, Sn)
Authors: Zeil Werner , Haas Bernhard
Published: March 2015

An einer Reihe von Chloracetylenen der Elemente der 4. Hauptgruppe wurden die Kernquadrupolresonanzspektren des 35Cl-Atoms vermessen. Aus diesen wurde die Kernquadrupolkopplungskonstante und nach der Theorie von TOWNES und DAILEY der π-Bindungsgrad der C—Cl-Bindung ermittelt. Die erhaltenen Resultate, die für eine starke Delokalisierung der π-Elektronen im Falle der Silicium-, Germanium- und Zinn-Verbindungen sprechen, werden mit anderen molekülphysikalischen Daten von Halogenacetylenen verglichen. Als Ergebnis resultiert, daß die von der Mesomerielehre geforderte Delokalisierung der π-Elektronen vorliegt und diese verstärkt wird, wenn Atome mit unbesetzten d-Orbitalen der Acetylengruppe benachbart sind.
Verlustmessung in Rubin-Lasern
Authors: Baasel C. F. , Pohl D.
Published: March 2015

The amplification of light in a laser ruby depends on the angle between the direction of polarization and the c-axis of the crystal. This leads to a changing threshold if the plane of polarization is rotated within the cavity. The change in threshold can be compared with the change produced by the addition of a definite loss in the laser cavity.

The method is simple because the cavity loss (including the loss in the ruby) can be determined immediately and without any assumptions on the dynamics of the laser. The loss of a ruby FABRY-PEROT laser and a ruby ring laser has been measured in this way.
Zur Diffusion von Xenon in neutronenbestrahlten Cs-Halogeniden
Authors: Felix F. W. , Meier K.
Published: March 2015

The release of Xenon-133 m and Xe-133 from neutron-irradiated single crystals of Cs-halides was measured in function of temperature and neutron dose. This release could be expressed in terms of volume diffusion. The temperature dependence in CsF, CsBr and CsI can be described by the activation energies ≦ 2, 1.45 and 1.14 eV and the frequency factors ≦ 1 × 102, 1 × 102 and 2.0 cm2/sec in the temperature regions 450—600, 260—580 and 200—500°C respectively. Increasing neutron doses decrease diffusion coefficients in CsBr and CsI.
Interdiffusion of 6Li and 7Li in Isotopically Nearly Pure Lithium Metal Melts
Authors: Löwenberg L. , Lodding A.
Published: March 2015

A capillary-reservoir technique has been used to investigate the interdiffusion of 6Li and 7Li in nearly pure (ca. 94%) 6Li, as well as in nearly pure 7Li. At the melting point the ratio of these diffusion coefficients is about 1.30. Extrapolation to tracer concentrations gives good qualitative agreement with the ratio of the viscosities of 7Li and 6Li. The interdiffusion coefficient ratio of the melts decreases with rising temperature, also in agreement with viscosity results. Quantum effects are likely to be responsible for the strong dependence on isotope mass.
Massenspektrometrische Untersuchung der Sekundärionen-Emission von Legierungen
Authors: Schelten Jakob
Published: March 2015

An alloy bombarded with 12 keV — Ar+-ions emits singly charged secondary ions (SI) of all components of the target. By measuring the SI-currents in a mass spectrometer a quantitative analysis is possible (Ion-bombardment ion source).

The SI-emission of aluminium and iron alloys with varying concentration of other components is investigated. It is shown that the relative SI yield, i. e., the ratio of the SI yield of the extra components to the yield of the main components aluminium and iron, respectively is independent of the composition of the sample provided that the sample contains more than 90% of the main component. This result is in qualitative agreement with the Langmuir-Saha-equation.
Die Bildung von Elektronenzentren in polykristallinem Natriumchlorid und Strontiumchlorid durch 60Co-γ-Strahlen
Authors: Rabe J.G.
Published: March 2015

The concentration of electron centers in polycristalline NaCl und SrCl2 has been determined by measuring the amount of hydrogen which is evolved when the irradiated salt is dissolved in an acid aqueous solution containing alcohol.

The time dependence of the formation of electron centers can be described by the same equation as was derived for F-centers in single crystals of NaCl and KCl. Grinding of salt results in the formation of additional negative-ion vacancies in the lattice. Their concentration can be determined from the growth curve of the electron centers. Grinding increased the concentration of negative-ion vacancies by about one order of magnitude.

For polycristalline SrCl2 a growth curve of electron centers similar to that of NaCl is obtained. In annealed samples of SrCl2 (750°C) the concentration of electron centers is one to two orders of magnitude lower at the same dose than in samples which have not been annealed.
Untersuchung heißer Elektronen in Halbleitern mit Hilfe der Feldelektronenemission
Authors: Neumann H.
Published: March 2015

Bei der Untersuchung der Feldelektronenemission aus hochohmigen Halbleitern ergeben sich Abweichungen vom linearen Kennlinienverlauf, die durch das Auftreten eines Spannungsabfalls am Emitter bedingt sind. Eine Analyse dieser Abweichungen ergibt Daten über die Feldabhängigkeit der Beweglichkeit der Elektronen im Emittermaterial. Messungen an In2S3 zeigen, daß vorwiegende Streuung an polaren optischen Phononen angenommen werden kann. Bei 77°K ist die Wechselwirkung mit akustischen Nullpunktsschwingungen, bei 195°K eine mögliche Streuung an ionisierten Störstellen zu berücksichtigen.
External Transport Numbers in Molten Zinc Bromide
Authors: Sjöblom C.-A. , Andersson J.
Published: March 2015

The external transport number 1 in pure molten zinc bromide has been measured as a function of temperature using a porous plug as velocity reference. The results can be described by the equation (obtained by least squares fitting)

tZn++=0.791 -3.68 x 10-4 (T-394) (469-562°C)

where T is expressed in degrees Centigrade. The result is in excellent agreement with values calculated according to the so-called “new formalism” developed by Laity 1, 2.
Anisotropie der Kernresonanzfluoreszenzausbeute an Si28 mit Aluminium-Einkristallquellen
Authors: Kalus J. , Thaler H. J.
Published: March 2015

Unter Ausnutzung einer β—γ-Zerfallskaskade kann an dem 1,772 MeV-Niveau von Si28 Kernresonanzfluoreszenz (KRF) beobachtet werden. Die Anisotropie der KRF-Ausbeute, die infolge der richtungsabhängigen Abbremsung der zerfallenden Siliciumkerne (Energie bis 215 eV) in einem Aluminium-Einkristall zu erwarten ist, wurde experimentell gefunden. In einem Richtdiagramm für die (110)-Ebene ergaben sich Schwankungen der KRF-Ausbeute bis zu 13%. Der mit einem verbesserten Hartkugelmodell unter qualitativer Berücksichtigung der Abbremsung berechnete Verlauf der KRF-Ausbeute stimmt mit dem gemessenen Verlauf befriedigend überein.
Zur Expansion künstlicher, neutraler Metalldampfwolken in der Hochatmosphäre
Authors: Smilga W.
Published: March 2015

A two-phase-flow model for the expansion of an artificial metal vapour cloud in the upper atmosphere is considered, which may account for the very high expansion velocity and the shell structure of some experimental clouds.
Zum nichtadiabatischen Verhalten der Kernbewegung eines H3-Systems
Authors: Wrzesinsky Rudolf
Published: March 2015

Es wird untersucht, inwieweit bei der Bewegung dreier Η-Atome im Grundzustand unter dem Einfluß ihrer chemischen Kraftwirkung aufeinander eine adiabatische Behandlung gerechtfertigt ist. Nähern sich die drei Kerne der Konstellation des gleichseitigen Dreiecks, so ist die Verkopplung der Bewegung in den beiden tiefsten Energieflächen zu berücksichtigen. Für die Umgebung des gleichseitigen Dreiecks mit Seitenlänge s=1,4 atomare Einheiten werden die Kopplungskoeffizienten näherungsweise berechnet. Die Ergebnisse dürften u. a. von Interesse sein für eine Untersuchung des H2—H-Stoßproblems im Hinblick auf einen Beitrag zur H2-Dissoziation auf Grund des nichtadiabatischen Verhaltens.
Schwingungen von Molekülen und Ionen des Typs XY4 mit D4h -Symmetrie und Massenabhängigkeit der Coriolis-Kopplungskonstanten
Authors: Cyvin S. J. , Cyvin B. N. , Müller A. , Krebs B.
Published: March 2015

Für alle Moleküle und Ionen des Typs XY4 mit D4h-Symmetrie, von denen Frequenzdaten bekannt sind, werden Kraftkonstanten, mittlere Schwingungsamplituden und Coriolis-Kopplungskonstanten berechnet. Es ergibt sich, daß die Coriolis-Kopplungskonstanten eine eindeutige Massenabhängigkeit zeigen.
Grundlagen und Anwendungen einer neuen Diffusionsmethode in flüssiger Phase 1
Authors: Dreyer G. , Kahrig E. , Kirstein D. , Erpenbeck J. , Lange Fr.
Published: March 2015

Es wird eine neue Diffusionsmethode angegeben, die darauf beruht, daß sich bei pulsierender Flüssigkeitsströmung in einem porösen oder lamellerten Diaphragma an den Poren- bzw. Lamellenwänden sehr stabile Flüssigkeitsschichten ausbilden, die, in wechselnder Richtung von sehr unterschiedlich konzentrierten Lösungen bespült, hohe Konzentrationsgradienten bei großen Austauschflächen zulassen. Bei geeigneter Anordnung kann der Stofftransport um mehrere Zehnerpotenzen gegenüber den bekannten Anordnungen gesteigert werden bei gleichzeitig sehr erheblich verminderten konvektiven Störungen.
Experimentelle Untersuchungen zur Dynamik elektromagnetisch angetriebener konvergenter Zylinderstoßwellen
Authors: Kogelschatz U. , Bötticher W. , Dammann H. , Kleist G.
Published: March 2015

In the convergent cylindrical shock wave of a Z-pinch discharge (diameter/length ratio : 44 cm per 10 cm), magnetic probe measurements have been made of the current density and the velocity of the current sheet. For discharges in Helium, Argon and Krypton at mass densities from 2.2·10-7 to 5.5·10-6 g/cm3 one finds: 1. Only a small portion of the total current contracts with the shock wave. The direction of this current is maintained even when the total current reverses. 2. The gas pressure behind the shock front is a constant for each gas independent of the filling pressure. 3. At small radii the contraction is determined by the inertia of the moving plasma only. 4. With higher filling pressures a considerable part of the small contracting current flows ahead of the shock front.
The Electrical Conductivity and Density of Pure Molten Thallium Sulphate and Equimolar Mixtures between Thallium Sulphate and Alkali Sulphates
Authors: Kvist Arnold , Schroeder Kjell
Published: March 2015

The electrical conductivity and density of pure molten thallium sulphate and the conductivity of TlMeSO4, where Me = Li, Na, K, Rb, or Cs, have been measured between 700 and 1150 °C. We have also measured the densities of four equimolar sulphate mixtures and their pure components. The excess volumes were less than 0.5%. The deviations from ideality for the conductivities and their Arrhenius activation energies have been compared with other sulphate systems. The electrical conductivity of a pure univalent sulphate depends both on the radius of the cation and on its mass. In mixtures, there are large negative excess conductivities and positive excess activation energies, when we have cations of different sizes.
Diffusion in Cubic Sulphates
Authors: Kvist Arnold , Bengtzelius Ante
Published: March 2015

The interdiffusion coefficients (D) of Na+, Ag+, K+, Rb* and Τl+ in pure f. c. c. Li2SO4 have been measured between 590 and 820 °C. D and the Arrhenius’ activation energies decrease in the same order as the ionic radii increase. D is a function both of the masses and the radii of the impurity cations. The results show that the Na+ and Ag* ions mainly diffuse in the sulphate lattice with the same mechanism as the lithium ions, while the larger ions are mobile in defects in the lattice. The Li*, Na+ and Ag* ions are probably diffusing between octahedral positions.
Abbildung von Erstarrungsprofilen mit Hilfe kurzer Ultraschallimpulse
Authors: Buxmann K. , Dürr S.
Published: March 2015

Es wird eine Methode zur Aufzeichnung der zeitlichen Entwicklung der Phasengrenze festflüssig während der Erstarrung von Metallen mit Hilfe kurzer, periodischer Ultraschallimpulse beschrieben. Die damit ermittelten Erstarrungsprofile stimmen in wesentlich höherem Maße mit den theoretisch geforderten überein als die nach dem üblichen Verfahren, dem Dekantieren, erzielten. In diesem Zusammenhang werden die Fehlereinflüsse beim Dekantieren kurz diskutiert.
Das Kombinationsschwingungsspektrum von Gips im Bereich von 10 000—1200 cm-1
Authors: Hohler V. , Lutz H. D.
Published: March 2015

The IR-spectrum of gypsum (CaSO4·2 H2O) in the frequency range from 10 000 to 1200 cm-1 has been investigated with polarized light at room temperature. Between 3700 and 1200 cm-1, the measurements confirm the data of HASS and SUTHERLAND and as well as those of SCHAAK derived from IR and reflection measurements. The IR-spectrum shows a great number of bands, most of which can be assigned to combination and fundamental vibrations in terms of normal vibrations of the water molecules and the sulfate ions. The influence of the lattice vibrations is briefly discussed. The existence of hydrogen bonds between the water molecules and the sulfate ions gives rise to combinations of fundamental vibrations of both complexes.
Photon-Counting as a Technique for Determining Correlations in a Plasma
Authors: Crosignani B. , Porto P. Di , Engelmann F.
Published: March 2015

It has been suggested 1 that counting photons scattered from a single-mode laser beam passing through a plasma, may be used for determining correlations in the plasma. Higher-order moments of the distribution of photon counts are related to an ensemble average of higher-order products of the electric field. Hence, this method yields also information about higher-order correlations of the electron density fluctuations, in contrast with the measurement of the scattering cross section which depends only on second-order correlations. In this paper, the connection between the statistics of photon counts and the properties of electron density fluctuations is discussed in detail, concentrating on the first and second moment of the photon count distribution. The incident wave is assumed to be plane and ideally monochromatic. For stable plasmas in a steady state, the results are written in terms of the distribution functions of the electron and ion velocities. Weakly turbulent unstable plasmas in the phase of exponential growth are also considered, using as a characteristic parameter the spectrum of the electric micro-field.
Mutual Gravitational and Collisional Scattering of Bodies in the Asteroid Belt
Authors: Wetherill G. W.
Published: March 2015

A calculation is made of the cumulative effect of numerous small orbital perturbations caused by gravitational and collisional deflections of meteorites by other bodies in the asteroid belt. It is found that in a time equal to the age of the solar system the mean change in perihelion distance caused by gravitational perturbation is of the order of 10-4 A. U.

This phenomenon is consequently of negligible importance in removing meteorites from the asteroid belt. This conclusion is in disagreement with a result reported in the recent literature. The calculated mean change in perihelion distance caused by multiple collisional scattering is somewhat higher, about 10-3 A. U. It is conceivable that a small fraction of very strong objects such as iron meteorites in highly inclined and eccentric orbits may be deflected into Mars-crossing orbits by this mechanism.
Non-Stationary E. M. F. Measurements after Polarization of Solid Galvanic Cells. The Stability of NbO
Authors: Barbi Giovanni B.
Published: March 2015

The open-circuit electrical potential of the solid galvanic cell :

was measured between 1000 and 1400 °K.

The measurements were carried out both in stationary and in non-stationary conditions after cathodic polarization of the Nb—NbO electrode, recording the e. m. f. decay curves.

A comparison between the two sets of results was made and the conditions which assure the reliability of the tensiometric measurements under non-stationary technique were stated.

The standard free energy of formation of niobium monoxide was then calculated from the experimental data.

The discrepancies with the literature values of the standard enthalpy and entropy of formation were interpreted in terms of a significant homogeneity field of stability of the NbO phase.
Dodekaeder und Archimedisches Antiprisma als Molekülstrukturen bei Oktacyanokomplexen des Molybdän(IV) und Wolfram(IV)
Authors: König Edgar
Published: March 2015

Infrared spectra (300—4000 cm-1) have been measured on the octacyanide complexes K4Mo (CN)8·2H2O and K4W (CN)8·2 H2O in aqueous solution, in the solid dihydrates, and in the solid anhydrous compounds. Comparison with relevent Raman data, particularly in the 2100 cm-1 region, provides conclusive evidence for the effective molecular symmetry of the M (CN)8
4- group in the different surroundings. In aqueous solution, the ions [Mo (CN)8]4- and [W (CN) 8] 4- assume the symmetry of an Archimedean antiprism, D4d . In the dihydrate crystals, the groups Mo (CN)8
4- and W (CN)8
4- approach the full D2d symmetry of a dodecahedron with triangular faces, possibly slightly distorted by packing effects. In the anhydrous compounds, the symmetry of these groups is considerably lower, very likely C8. Reasonable assignments for all normal frequencies in the 2100 cm-1 region are proposed, both in D4d and D2d symmetry.
Raman-spektroskopische Untersuchung der Breite einiger totalsymmetrischer Thiophen-Schwingungsbanden in flüssiger Phase
Authors: Döge G.
Published: March 2015

Es wurde die Temperatur- und Konzentrationsabhängigkeit der Halbwertsbreite einiger Thiophen A1-Schwingungen untersucht. Die Messungen zeigen, daß ein Teil der Bandenbreite bei gewissen Schwingungen proportional mit der Verdünnung abnimmt. Temperaturabnahme führt bei den gleichen Schwingungen zur Verbreiterung der Banden. Die Abnahme der Bandenbreite bei Verdünnung ist nicht meßbar vom Dipolmoment der Moleküle des Mischungspartners abhängig. Diese drei wesentlichen Ergebnisse lassen darauf schließen, daß der hier untersuchte Anteil der Bandenbreite durch Resonanzverbreiterung hervorgerufen wird.
Thermoelectric Properties of Fused Alkali Nitrate—Silver Nitrate Systems
Authors: Sinistri Cesare , Margheritis Chiara
Published: March 2015

In a thermocell with silver electrodes the thermoelectric power ε at zero time of the molten systems (Ag + Rb)NO3 and (Ag + Cs) NO3 at various temperatures has been measured.

These data, combined with previous measurements 1, allow to obtain information about the heat and electricity transport phenomena in the fused systems (AgNO3+alkali nitrates).
Die Bestimmung von Defekten in polykristallinem NaCl aus der Bildung von Elektronenzentren durch 60Co-γ-Strahlen
Authors: Rabe J. G. , Joppien G.
Published: March 2015

The concentration of electron centers in polycrystalline NaCl formed during irradiation has been determined using a chemical method previously described. The influence on the formation of electron centers under irradiation, of thermal treatment, Ca++ doping and grinding of the salt has been studied.

The growth of electron centers with time of irradiation was found to obey the equation given by Mitchell, Wiegand and Smoluchowski. In this equation occur the two types of anion vacancies present prior to irradiation, the rate of formation of new vacancies and the rates of center formation from initial and new vacancies.

Consistent with the Crawford-Nelson mechanism, the concentration of electron centers increases proportionally with the square root of the Ca++ concentration. At a Ca++/Na+ ratio of 2.5 × 10-4, about 11 Ca++ are needed to form an additional electron center.

The formation of defects by grinding the salt depends on its thermal pretreatment as well as on its Ca++ concentration. Most of the defects formed during grinding anneal when the salt is stored in moist air. When azoethane is adsorbed on preirradiated NaCl, the concentration of electron centers decreases. A quantitative evaluation of this effect leads to the conclusion that the concentration of defects formed by grinding the salt is orders of magnitude higher near the surface than in the bulk.
Näherungslösungen für die Form kernmagnetischer Signale bei Impulsexperimenten in Festkörpern
Authors: Siegle G.
Published: March 2015

NMR transients in solids have been calculated using the method of LOWE and NORBERG 1 and its extension by POWLES and STRANGE 2. Some remarks are given concerning the evaluation of the formal solution for the signal after several pulses.

So far the influence of the pulse durations and of the longitudinal relaxation is neglected usually, higher terms of the power series expansion of the signals were discussed only with respect to corrections of their amplitudes. Some remarkable differences between these calculations and new experimental results to be reported here are explained — at least in principle — avoiding these limitations:

The maximum amplitude of the echo after two 90°-pulses (phase difference of their modulations Δφ=90°) occurs not exactly at a time twice the pulse distance, the deviation is explained considering the duration of the pulses and the decay of the echo envelope.

After two pulses with Δφ=0° an echo was found which should disappear only in an ideal twospin system. For a three pulse sequence the influence of the longitudinal relaxation is described; and in a multi-pulse sequence the calculated modulation of the amplitude of successive echoes was checked by experiments.
Oberflächenstrukturen nach Sauerstoffadsorption auf kugelförmigen Kupfereinkristallen
Authors: Trepte L.
Published: March 2015

The surfaces of spherical copper crystals were investigated by HEED (60 keV electrons). Grown by solidification of a drop of melt in high vacuum the untouched crystals only show diffraction patterns from the clean copper.

After adsorption of oxygen from 10-4 to 5·10-3 torrmin. air at 800 °C extra spots appear in the diffraction patterns. They are characteristic of diffraction from twodimensional surface structures. Special structures due the adsorption of oxygen are reported for the (001), (011), (014), (223) and (035) surfaces not only for these poles but also for their surroundings. On the high indexed surfaces (014), (035) and (223) (1 × 1)-adsorption structures were observed. No adsorption structures were obtained on (111) and (112). A vacuum anneal of 400 °C destroys the adsorption structures by solution of the oxygen atoms into the bulk of the copper crystals.

The adsorption structures and the boundaries of their domains do not show a relationship to the known epitaxy of threedimensional Cu2O on Cu.
Der Compton-Effekt an relativistischen Elektronen
Authors: Haug Eberhard
Published: March 2015

Für den Compton-Effekt an bewegten Elektronen wird der differentielle Wirkungsquerschnitt dσ/dk2 (k2 = Energie der gestreuten Photonen) als Funktion des Winkels Θ1 zwischen dem einfallenden Photon und Elektron berechnet. Mit Hilfe einer daraus gewonnenen Näherungsformel für hohe Elektronenanfangsenergien ε1 und Photonenenergien k1 ≪ ε1 wird der mittlere effektive Wirkungsquerschnitt Φ̅ (ε1, k1, k2) bei isotroper Photonenverteilung abgeleitet. Man erhält eine Verallgemeinerung der Formel von GINZBURG und SIROVATSKIJ. Der Wirkungsquerschnitt ist für verschiedene Elektronenenergien, die auch in der Astrophysik von Bedeutung sind, graphisch dargestellt.
Veränderungen charakteristischer Valenz-Frequenzen zweiatomiger organischer Gruppen beim Übergang vom Dampf in die flüssige Phase
Authors: Ulbrich R.
Published: March 2015

Mathematical treatment of characteristic stretching frequency shifts of diatomic groups in the case of transition from vapour to the fluid phase. The shift is a sum of a dispersion forces term and a dipole orientation term. The derived formula is in qualitative agreement with experimental data found by other authors.
Quantenmechanische Verteilungsfunktion für ein Elektronengas
Authors: Schmitz G. , Kremp D.
Published: March 2015

The reduced distribution functions for an electron-gas are calculated from the Bogoljubow hierarchy by a perturbation expansion of the density operators with respect to two parameters. The limiting cases n λ3 ≪ 1 and n λ3 ≫ 1 are discussed. In the case n λ3 ≫ 1 the polarization function for small values of the temperature T ≠ 0 is given.
Heisenberg’s Statistical Theory of Turbulence and the Equations of Motion for a Turbulent Flow
Authors: Winterberg F.
Published: March 2015

It is shown that consistent with Heisenberg’s statistical theory of turbulence, equations of motion for a turbulent flow can be derived. These equations are linear integro-differential equations expressing the non-local interaction of eddies with different wave numbers on the basis of Heisenberg’s statistical theory.

The nonlocal terms in these equations of motion for turbulent flow have to be determined from the energy spectrum of the turbulent motion, which is obtained from a nonlinear integro-differential equation. A general solution of the linear equations of motion is obtained by an arbitrary superposition of solutions. However, only those linear superpositions are permitted which are selfconsistent with the energy spectrum of turbulent motion.

In contrast to the Navier-Stokes equations, the non-linearity occurs here only in the equation for the energy spectrum and not in the equations of motion itself. This fact greatly facilitates the integration of these equations.

Our analysis is extended to include turbulent convection. In the spirit of Heisenberg’s hypothesis, equations of motion and energy are formulated which are consistent with the equations of the energy spectrum for free turbulent convection derived by Ledeoux, Schwarzschild and Spiegel. With this method, one may treat turbulent convection problems which arise in stellar and planetary atmospheres where the classical solution of laminar free convection cannot be applied.
Röntgenographische Untersuchungen an aufgedampften Nickelfilmen
Authors: Wedler G. , Wissmann P.
Published: March 2015

Nickelfilme mit Schichtdicken zwischen 100 und 4000 Å wurden unter verschiedenen Bedingungen auf Tempaxglasträger aufgedampft und anschließend mit Hilfe eines Texturanalysators röntgenographisch untersucht.

Es zeigt sich, daß die Textureigenschaften der Filme in starkem Maße von der Schichtdicke und der Temperungstemperatur abhängig sind. Während die Kristallite in den schwach getemperten Filmen keine merkliche Vorzugsorientierung aufweisen, findet man bei den hoch getemperten Filmen eine 〈111〉-Fasertextur, die besonders bei großen Schichtdicken stark ausgeprägt ist. Sie kann darauf zurückgeführt werden, daß während des Temperns die nach {111} orientierten Kristallite unter dem Einfluß des unterschiedlichen thermischen Ausdehnungskoeffizienten von Film und Unterlage bevorzugt wachsen.
Zur Theorie des Wien-Effektes in nichtassoziierenden Elektrolyten
Authors: Kraeft W. D. , Ulbricht H. , Kelbg G.
Published: March 2015

The Wien effect in symmetrical electrolytes is computed. The model used is: rigid charged spheres in a continous solvent. The correlation function is calculated to the order of E3 and b (E field strength, b = e2/(DkTα)-Bjerrum’s parameter). The constant A in the formula

(σ(E) — σ(E = 0))/σ0(E = 0) = AE2 + BE4 + ... (here σ0(E = 0)

is the conductance of noninteracting ions) is calculated to be of the form

A = [e/(kTx)]2 xαb (A0 + xαA1(b)) + [e/(kTx)]2(xρ/πη)(Βo + xα B1(b)).

The two parts are the contributions of the relaxation force and of the electrophoresis, respectively. In the case a = 0 our result is in agreement with that of Wilson.
Extremaleigenschaften von Kraftkonstanten
Authors: Strey G. , Klauss K.
Published: March 2015

Unter der Voraussetzung, daß ein Diagonalelement Fii der Matrix F des Potentialansatzes der Schwingungsbewegung eines Moleküls extremal ist, werden allgemeine Eigenschaften der Schwingungsformen, also der Matrix L der Eigenvektoren der Säkulargleichung (GF) L = LA abgeleitet.
Zur Strömung im asymmetrischen kurzen Rohr
Authors: Frie W. , Jäger Ph.
Published: March 2015

Zur Beschreibung der Strömung in einem Rohr steht die Kennlinie für die ungestörte Rohrströmung zur Verfügung. Außerdem sind die durch Ein- und Ausströmöffnungen verursachten Zusätze zum Druckgefälle für den Fall voller Turbulenz in der Literatur behandelt. Es sind auch weiterreichende theoretische Untersuchungen unter vereinfachenden Voraussetzungen bekannt. Die Abhängigkeit des Druckabfalles an einem asymmetrischen kurzen Rohr von der Durchflußgeschwindigkeit im Übergangsgebiet zwischen laminarer und turbulenter Strömung läßt sich damit nicht befriedigend wiedergeben. In der vorliegenden Arbeit werden die theoretischen Überlegungen zur ungestörten Rohrströmung auf die „gestörte Strömung im kurzen Rohr“ erweitert und mit Messungen verglichen. Es ergibt sich dabei eine gute Übereinstimmung zwischen Theorie und Experiment.
The Temperature Dependence of Isotope Thermotransport in Liquid Metals
Authors: Löwenberg L. , Nordén-Ott A. , Lodding A.
Published: March 2015

The isotope effect due to temperature gradient has been investigated in liquid K and Rb, using new type steel capillary cells, convenient for the study of the variation of the effect with temperature. The physical parameters, deduced from the experimentally determined steady state gradient of the isotope separation factor versus reciprocal temperature, agree with earlier results obtained within restricted temperature ranges, and were found to be nearly independent of temperature.
Influence of a Magnetic Field on the Brownian Motion of Particles with Magnetic Moment
Authors: Hess Siegfried
Published: March 2015

The influence of a magnetic field on the diffusion of Brownian particles with a magnetic moment parallel to their internal angular momentum is discussed. Starting point is a generalized Fokker-Planck equation. Application of the moment method leads to a set of transport-relaxation equations. From them the diffusion tensor depending on the external field is inferred.
Ladungszustände von Lithiumionen nach dem Durchdringen von Materie
Authors: Wendt M. , Haktung J.
Published: March 2015

Charge distributions of lithium ions after passage through different gas and foil strippers are measured in the energy range between 0.5 and 2 MeV. The ratios of the equilibrated beam components with charge i and k (Fi∞/Fk∞) were found to obey simple power-laws. A density effect of about 15% was observed. Measured charge distributions are compared with calculated. Relatively good agreement could only be reached with the method of DMITRIEV using shell-dependent probability functions of HECKMAN. An empirical expression for the average equilibrium charge q as function of the particle energy is given and discussed.