bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermodynamic Investigations of Thin Liquid Layers Between Solid Surfaces III. Benzene Between Differently Polar Fused Silica Surfaces
Authors: Peschel G. , Adlfinger K. H.
Published: February 2015

Former measurements showed that benzene exhibits a disjoining pressure in extremely thin layers between fused silica plates in a temperature range just above the melting point. An extended theory for evaluating the disjoining pressure and various thermodynamic quantities of the liquid surface zone which displays a molecular long range orientation leads to results which indicate a small structural transition range at about 12 - 13 °C in bulk benzene. The splitting effect is more pronounced in layers adjacent to fully hydroxylated surfaces since in this case the benzene mole­cules in the first adsorbed layer are more tightly bound than in the case of surfaces entirely free from hydroxyl groups.
Temperature Dependence of Electrical and Thermal Resistivities of Noble Metals
Authors: Semwal B. S. , Mehrotra P. K. , Mehrotra K. N.
Published: February 2015

The electrical and thermal resistivities of noble metals copper, silver and gold have been de­termined at different temperatures in the free electron approximation using Sharma and Joshi's model for the phonon dispersion relations. A modified Houston's method is used to evaluate the formidable integral over the scattering vector. The normal and Umklapp contributions to the resistivity are considered separately from the conservation laws of wave vector. The theoretical and experimental resistivity curves are found to be of similar nature, but the agreement is not detailed. The Lorentz numbers of noble metals deduced from theoretical and experimental resistivity data show considerable deviation from Wiedemann-Franz law.
Production and Annihilation of Triplet Excitons in Organic Materials near Absorbing Surfaces
Authors: Kallmann H.
Published: February 2015

The theory of delayed fluorescence produced in an organic material by singlet excitation through an absorbing layer is given. It is shown, that it will be reduced by a factor la
2/(la +ls)2 due to the singlet energy transfer to such a layer, where U the penetration depth of the exciting irradiation and I3 the diffusion lenght of the singlets. Further reduction of delayed fluorescence should be observed, when also triplet excitons transfer energy to the absorbing layer. Assuming this triplet transfer probability to be of the same order of magnitude as that for triplet energy transfer between neighbouring molecules, it should lead to quenching of delayed fluorescence proportional to la
2/lt
2 .The exponential portion of the decay of delayed fluorescence should become faster only if triplet energy transfer to the layer takes place. Further, the triplet induced hole-current produced at an absorbing electrode under singlet excitation should display a dependence on the wavelength of the exciting radiation as la(la + ls). Its maximum should not occur at the wavelength of strongest absorption but at much larger penetration depths of the exciting radiation.
Electroluminescence in Mylar Films
Authors: Bässler H. , Rasskopf K. , Vaubel G. , Reinke K.
Published: February 2015

Non-destructive electric breakdown through mylar films is associated with emission of an intense light flash. Within an active volume of about 4×10-8 cm3, L ≧ 109 photons are generated during a current pulse. L is proportional to the number of transported charge carriers (electrons) and independent from sample thickness. The emission spectrum is a superposition of ordinary mylar fluorescence centered at 370 nm and impurity bands at longer wavelengths. Interpretation is given in terms of acceleration of injected electrons within the positive cathodic spacecharge zone giving rise to both impact excitation and ionization, predominantly involving guest molecules.
Thermodynamik heterogener Gasgleichgewichte I. Freie Bildungsenthalpie ΔGB
0 der Verbindungen in den Wolfram-Halogen-Systemen
Authors: Neumann G. M. , Knatz W.
Published: February 2015

Zur Beurteilung der chemischen Transportreaktionen in den Wolfram-Halogen Systemen werden nach dem Verfahren der 3. Ulichschen Näherung Gleichgewichtskonstanten Kp und freie Bildungs­ enthalpien ΔGB° der Verbindungen WF2 , WF4 , WF5 , WBr2 , WBr4 und der hypothetischen Verbindungen WJ, WJ2 , WJ4 , WJ5, WJ6 bis zur Temperatur des flüssigen Wolframs ermittelt.

Im Zusammenhang mit bekannten Daten zeigt sich, daß in den Systemen Wolfram-Chlor und Wolfram-Brom die Reaktionen über die Verbindungen WX4 und WX2 ablaufen, während im System Wolfram-Fluor daneben die Verbindungen WX5 und WX6 eine Rolle spielen. Die Daten des Systems Wolfram-Jod zeigen, daß die reinen Wolfram-Jod-Verbindungen energetisch nicht stabil sind. Die in der Literatur beschriebenen experimentellen Befunde von der Nichtexistenz dieser Verbindungen werden dadurch vom Standpunkt der Thermodynamik bestätigt.
Über die elektronischen Energieniveaus des N-Isopropylcarbazols und seiner Radikalionen 2. Teil: Elektronenspinresonanzspektren
Authors: Klöpffer W. , Kaufmann G. , Naundorf G.
Published: February 2015

Well resolved spectra have been obtained from the radical anion of N-isopropylcarbazole (NIPCA). The splitting parameters have been evaluated by simulation of the spectrum. It is shown that in accordance with HMO calculations the spin density at the nitrogen atom is very small. The poorly resolved NIPCA·+ spectrum points to a high spin density at the nitrogen atom. The mean square zero field splitting parameter of NIPCA is identical with that reported for carbazole.
Self-Diffusion, Conductivity and Transport Numbers in Alkali Halide Single Crystals
Authors: Beniere Franqois , Beniere Michelle , Chemla Marius
Published: February 2015

The self-diffusion coefficients of the anions and cations have been measured in pure and doped NaCl and KCl crystals, together with the ionic conductivity. The experimental results give evidence for migration mechanisms via free cation and anion vacancies and vacancy pairs. Analysis of the complete set of diffusion data leads to the determination of the entropy and enthalpy of formation and migration of these defects.

In a second part, the diffusion coefficients via free vacancies are compared with the conductivity data in order to investigate the validity of the Nernst-Einstein relation. This relation is found to be verified within 2%, in NaCl as well as in KCl, no appreciable correlation effect being detected.
The Existence Diagram — A Useful Theoretical Tool in Applied Physics
Authors: Ecker G.
Published: February 2015

The complexity of theoretical work in physics applications often forces severe neglections and crude approximations. Insufficient experimental knowledge of important parameters increases the uncertainty. In this situation the E-diagram method still allows to arrive at useful results through controlled choice of the approximations and sensible limitation of the aims. Choosing “unidirected” deviations only, existence limits can be calculated which restrict the existence of the system to a narrow region - the existence area - of the coordinate plane of variables under consideration. The example of the vacuum arc cathode demonstrates the procedure and its suitablility.
On the Senftleben-Beenakker Electric Effect in Gaseous Ammonia
Authors: Levi A.C. , Tommei G.E.
Published: February 2015

The viscosity of gaseous ammonia in the presence of a static homogeneous electric field is calculated using the Waldmann-Snider equation. Special attention is paid to the field dependence of the effect which is strongly influenced by molecular inversion. The latter causes a coupling of tensors of different rank in J in the expansion of the distribution matrix, thereby leading to an infinite set of equations which is solved numerically by a limiting procedure. The effect has a complicated dependence on pressure p and field E but to a good approximation turns out to depend on E/p a t pressures high with respect to an inversion pressure (about 5 atm for NH3, 300 torr for ND3) and, in agreement with the experiments, on E2/p at low pressures.
Untersuchung des 5p2P3/2-Terms im Silber I-Spektrum durch Resonanzstreuung von Licht in elektrischen und magnetischen Feldern
Authors: Bucka H. , Einfeld D. , Ney J. , Wilken J.
Published: February 2015

Using separated isotopes the hyperfine structure of the 5p 2P3/2-state in Ag I-spectrum was investigated by scattering the resonance line on an atomic beam in parallel magnetic and electric fields. With the theoretical positive sign of the Stark-constant β, the shift of the Heydenburg- and level-crossing-signals with electric fields can be explained by the following parameters:

Ag (107) : A = - (32,4 ± 0.5) Mc/sec ,

Ag (109): A - - (37,3 ± 0.8) Mc/sec ,

β (2P3/2) = (5.15 ± 0.15) (kc/sec) (kV/cm) -2 ,

τ (2p3/2) = (6.3 ± 0.6 ) · 10-9 sec.
Kinetic Theory for a Dilute Gas of Particles with "Spin"
Authors: Hess S. , Waldmann L.
Published: February 2015

The Senftleben-Beenakker effect of the viscosity of dilute polyatomic gases is investigated theoretically for the case where an alternating magnetic field parallel to the usual static field is present. The starting point is a set of transport-relaxation equations obtained from the kinetic equation for the one-particle distribution by application of the moment method. The transport-relaxation equations are solved for the viscosity problem and the relevant viscosity coefficients averaged over many periods of the oscillating field are calculated as functions of the frequency of the alternating field and of the magnitudes of both magnetic fields. The importance of the obtained results for the dynamic behaviour of the thermomagnetic gas torque (Scott effect) is discussed.
Lösungskalorimetrische Bestimmung der Energieaufnahme von naßvermahlenem Aluminiumpulver
Authors: Wagendristel A. , Berger R.
Published: February 2015

Gitterdefekte erhöhen den Energieinhalt eines Festkörpers. Dies zeigt sich bei chemischen Umsetzungen in einem zusätzlichen Beitrag zur Reaktionsenthalpie. Im folgenden wird über die Veränderung der Lösungswärme von Aluminiumpulver durch eine Sdiwingmahlbehandlung mit steigender Mahldauer berichtet. Die Zunahme der Lösungswärme entspricht den bei einer Wärmebehandlung ermittelten Werten der Speicherenergie1.
Messungen der Bildfehler eines elektrostatischen Sektorfeldes / Measurement of Image Aberrations of an Electrostatic Sector Field
Authors: Bäuml Alfred
Published: February 2015

The ion-optical properties of a cylinder-condenser (sector angle φ = 50° and curvature radius of the middle equipotential surface r0 = 100mm) are investigated by an experimental ray-tracing technique.

A narrow electron beam entering the field under a known angle and at a known place is observed on the exit side of the field by means of a luminescent screen combined with a special micro-scope. The measurement of the lateral distances of this ray from the central beam in several distances behind the exit field-boundary yields the information about the imaging properties of the sector field. The analysis of the measurements indicates the existence of a third-order angular aberration. The experimentally determined values of second-order α-, u-, and δ-aberration-coefficients do not differ substantially from the theoretical ones.
Das Verhältnis der Flußdichten thermischer und intermediärer Neutronen in der Umgebung von Neutronenquellen im Wasser
Authors: Bortfeldt H. J. , Matzke M.
Published: February 2015

Measuring the cadmium-ratio as function of the distance from (α,n) -neutron sources in water we found a clearly distinguishable maximum followed by a small decrease with increasing distance. This behaviour can be explained by a calculation in diffusion approximation using special source terms.
Streuung von Ionen. III. Regenbogeneffekt bei der Streuung von H+ an N2 , CO, CO2 , SF6, H2 und CH4 sowie von H2
+ an Ar und Kr
Authors: Mittmann H.-U. , Weise H.-P. , Ding A. , Henglein A.
Published: February 2015

Differential scattering cross sections of H+ on various molecules and of H2
+ on Ar and Kr were measured at various energies between 5 eV and 40 eV. Several rainbows could be resolved for the systems H+-N2, H+-CO, H+-CO2 and H+-SF6 . In the case of H+-H2 , secondary rainbows could be traced at higher energies (30 eV). Only the primary rainbow was observed for H+-CH4 . The H2
+-Ar and H2
+-Kr systems also yielded rainbow structures. Broad additional maxima appeared at large angles for H2
+-Kr which were atttributed to the crossing of potential curves. The rapid oscillations could not be observed. The measured differential cross sections for the systems H+-N2 , CO, CO2, SF6 and H2 were fitted by a procedure described in part I using a simple Morse potential. The equilibrium distances rm were estimated from the relation rm = 0.7-rg (rg: gaskinetic radius of the molecule) which was found to hold approximately for the H+-noble gas systems.

The following potential depths e were obtained: 4.15 eV for N2-H+; 4.70 eV for CO-H+; 5.10 eV for CO2-H+; 3.66 eV for SF6-H+; 4.04 eV for H2-H+. These values are averages because of the anisotropy of the potentials. The potential depth for the H+-H2 system is little smaller than the theoretical value of 4.56 eV. This is attributed to nontriangular configurations in the scattering process. The scattering experiments with the system H4-CH4 were evaluated classically, ε (H+-CH4) was found to be 3.8 eV only. The large difference to the theoretical value ε = 5.45 eV is explained by the inadiabacity of the scattering process with respect to the movement of the H atoms in methane.

ε (Ar-H2
+) and ε (KrH2
+) were found to be (1.3 ± 0.2 ) eV and (1.1 ± 0.2 ) eV, respectively. Energy level diagram are dicussed for the ion-molecule reactions Ar+ (Kr+) + H2 → ArH+ (KrH+) + H including the ArH2
+ and KrH2
+ intermediate states. They show that most of the reaction energy becomes free in the approach of the reactants Ar++H2. This effect is less pronounced for the Kr+ (2P1/2)+H2-reaction and even a small threshold energy exists for the Kr+ (2P3/2)+H2-reaction. reaction
Monte-Carlo-Rechnungen zur Rückstreuung von schweren, hochenergetischen Ionen an Metalloberflächen
Authors: Güttner Klaus
Published: February 2015

A Monte-Carlo-Method is applied to describe the backscattering of high energy heavy ions from metal surfaces taking into account the energy losses. The calculations yield the angular and energy distributions of the reflected particles together with the percentage distributions of the complete particle histories. Furthermore it is possible to get informations concerning penetration depths and the number of collisions during the interaction of these particles with the metal foils. The calculated distributions are in good agreement with known experiments
Schweratomwirkungen von Hg(II) auf das Lumineszenzverhalten von Thionaphthen, Acenaphthen und Coronen
Authors: Zander M.
Published: February 2015

Die Mehrzahl der vorliegenden Untersuchungen über innere und äußere Schweratomeffekte (Zunahme der Spin-Bahn-Kopplung) in der Lumineszenz aromatischer Systeme bezieht sich auf Halogen als Schweratom 1. - In dieser Mitteilung wird über den Einfluß von Hg (II) (ZHg = 80) auf das Lumineszenzverhalten von Thionaphthen, Acenaphthen und Coronen beriditet.

Zum Studium des inneren Schweratomeffekts erscheinen die Aryl- bzw. Heteroaryl-Hg (II)-acetatverbindungen geeignet, die in vielen Fällen durch Umsetzung des Aromaten mit Hg (II) -acetat leicht zugänglich sind. - Im Rahmen dieser Arbeit wurde aus Acenaphthen ein Di-mercurierungsprodukt dargestellt, für das auf Grund des bekannten Verhaltens des Acenaphthens bei der elektrophilen Substitution und des IR-Spektrums (γ- CH-Schwingungen) die Konstitution I angenommen werden muß. Thionaphthen liefert in der gleichen Reaktion das Monomercurierungsprodukt II 2
Defects in Neutron-Irradiated ZnO (II)
Authors: Leutwein K. , Schneider J.
Published: February 2015

By ESR, it was observed that fast neutron irradiation of iron- and copper-doped ZnO results in association of diamagnetic lattice defects with the 3d-impurity ions
Zeeman-Effekt in der Phosphoreszenz von Naphthalin-Mischkristallen
Authors: Kilpper D. , Schowerer M.
Published: February 2015

The Zeeman splitting of the phosphorescence (T1→ S0) was investigated in a mixed crystal of perdeuterated Naphthalene (N-d8) and Naphthalene (N-h8). The N-h8 concentration varied between 0.2 and 5%, the temperature was 4.2 °K and the magnetic field strength was 50 kG. The intensity of the Zeeman components is strongly dependent on the direction of the field with respect to the molecular axes. In addition to this anisotropy we observe a strong anisotropy of the lifetime of the triplet state. Both these anisotropics are due to the zero field splitting of the triplet state T1. Their analysis yields the following constants: (1) the relative radiative transition probabilities kx
r, ky
r and kz
r from the three zero field components Tx, Ty and Tz to the singlet ground state S0 and (2) the total lifetimes tx , ty and tz of each zero field component. No assumptions concerning selection rules are made in the analysis. The results for the values of the ku
r (u-x, y, z) depend on the vibronic state of S0: if totally symmetric states are excited, 97% of the phosphorescence originates from the zero field component Tx . If the Δṽ= 1629 cm-1 B3g-vibration is excited the phosphorescence originates mainly from Ty and Tz . The total lifetimes of Tx , Ty and Tz are the same as measured previously in low fields by ESR.
Application of a New Principle of Assignment to the Infrared Spectrum of 2-Chloroacrylonitrile
Authors: Wlnther F.
Published: February 2015

The principle of phase independent anharmonicity constants has been applied to the assignment of the infrared spectra of gaseous and liquid 1-chloro-1-cyanoethylene. The transferability of the anharmonicity constants of 1,1-dichloroethylene and some other objective criteria have also been utilized. An attempt has been made to correct for vibrational resonances and to determine the harmonic frequencies of H2C:CCl(CN).
Statistical Thermodynamics Enthalpy, Free Energy, Entropy, and Heat Capacity of Some Hexafluorides of Octahedral Symmetry
Authors: Nagarajan G. , Brinkley Donald C.
Published: February 2015

A detailed analysis of the molecular structural data and infrared absorption and Raman spectra of the hexafluoride of sulfur, selenium, tellurium, molybdenum, technetium, ruthium, rhodium, tungsten, thenium, osmium, iridium, platinum, uranium, neptunium, and plutonium has been made. These molecules, having the greatest number of symmetry elements of all existing molecules, possess an octahedral symmetry with the symmetry point group Oh. They give rise to six fundamental frequencies of which three are allowed in the Raman spectrum, two are allowed in the infrared absorption spectrum, and one is inactive. The inactive mode in normally determined from the overtones and combinations. On the basis of a rigid rotator and harmonic oscillator model, enthalpy, free energy, entropy, and heat capacity for temperatures from 200 °K to 2000 °K have been computed for these molecules. The results are briefly discussed and compared with available experimental data.
Ein Näherungsverfahren zur Berechnung rotationssymmetrischer elektrostatischer Felder mit beliebigen Randbedingungen und seine Anwendung auf einen Elektronenstrahlerzeuger mit Spitzenkathode
Authors: Rauh Hermann
Published: February 2015

An approximate method is described for calculating electrostatic fields of rotational symmetry with arbitrary boundary conditions. The method is based on the computation of the surface charge density on the field forming electrodes. Successfully tested by well-known analytical solutions, the method is applied to the determination of electron trajectories in an electron gun with a point cathode. The ray tracing is done by the Runge-Kutta-Nyström procedure.
Die Austauschwechselwirkung in CeRu2 und seinen Mischkristallen mit den Rutheniden anderer seltener Erdmetalle
Authors: Hillenbrand B. , Schuster K. , Wilhelm M.
Published: February 2015

Für CeRu2 und seine Mischkristalle mit den Rutheniden anderer seltener Erdmetalle wird nach drei Methoden ein Wert für die effektive Austauschwechselwirkung J eff ermittelt: Aus der g-Ver-schiebung, aus der Konzentration c0, die den supraleitenden Konzentrationsbereich begrenzt, und aus Curietemperaturen. Die beiden ersten Methoden ergeben ein J eff von einigen meV, nach der dritten Methode ist J eff merklich größer. Es wird angenommen, daß die Ursache für die geringe Tc-Absenkung durch magnetische Ionen der seltenen Erdmetalle ein kleines J eff ist und nicht die Wechselwirkung der Ionen mit Kristallfeldern.
Verschiedene Formen von amorphem Selen
Authors: Richter H. , Breitling G.
Published: February 2015

Amorphes Se ist gitterähnlich. Weitere gitterähnliche amorphe Stoffe sind: Si, Ge, As, Sb u. a. m. sowie die Gläser SiO2 , B2O3 u. a. m. Diese amorphen Stoffe haben mit dem zugehörigen Gitter den Grundbaustein, das Bauelement, gemeinsam.

Bei Se hat man die drei amorphen Formen Se(I), Se(II) und Se(III) mit verschiedenem kürzestem Kettenabstand zu unterscheiden. In Se(I) kommen Schraubenketten wie im Gitter vor, in Se(II) und Se(III) dagegen ebene Zickzackketten mit dem Elementardreieck des Gitters als Baustein. In aufgedampftem amorphem Se findet man bei tiefer Temperatur Se(II) und bei Zimmertemperatur Se(III). Geschmolzenes Se von 270 °C baut sich vornehmlich aus Se(III) auf, daneben trifft man kleinste Gitterbereiche, also Se(I), an. Diese Struktur, und zwar mit denselben Komponenten, beobachtet man häufig bei glasig erstarrtem Se. In geschmolzenem Se von 425 °C liegt eine stark gestörte Kettenstruktur vor, so daß sich nur noch die Abmessungen des Elementardreieckes in der Atomverteilungskurve abzeichnen.
Modelle kraftfreier Magnetfelder
Authors: Wagner R.
Published: February 2015

A method for computing force-free magnetic fields of known anomality a ≠ const is described. The procedure is introduced by treating plane fields; thereby it is proved that force-free fields of constant strength are alyaws plane. In general case the surfaces a= const are chosen as coordinate surface of an orthogonal curvilinear coordinate system. In this system the magnetic field is described by a linear partial differential equation which can be solved numerically. Making use of simplifying assumptions about symmetries in the coordinate systems, analytic solutions are found which are extended on constant a.

The formulae derived can be used to decide if to a given geometry a force-free field does exist. Existing fields can be computed immediately. The results are illustrated by examples.
Erfahrungen zur numerischen Stabilität der Zentrifugalanalyse
Authors: Typke Volker
Published: February 2015

The numerical properties of 2 equivalent formulas for centrifugal distortion analysis are discussed The numerical results for 1-Chlor-3-Fluor-Propin and Dimethylsulfoxide show that the alternative formula to Watson's commonly used formula is numerically more stable by several orders of magnitude.
Comments on a Proposed Quantization of Interacting Fields
Authors: Schröder U. E.
Published: February 2015

The meaning of a recently proposed formalism for quantization of interacting fields is discussed by studying the consequences of the time-dependent unitary transformation which is essential for this approach. It turns out that non-relativistic quantum electrodynamics in dipole approximation may serve as a useful, although rather singular, example for this method. In the relativistic case a different point of view is suggested in order to avoid inconsistent interpretation. It is further possible to give arguments for a reasonable choice of the unitary transformation concerned
Die Beeinflussung der optischen Absorption von Molekülen durch ein elektrisches Feld
Authors: Liptay W. , Walz G.
Published: February 2015

The optical properties of molecules may he affected by an electric field. With suitable molecules, these effects allow to determine the electric dipole moments and certain components of the polarizability tensors in the ground state and in excited electronic states, the directions of transition moments and certain components of the transition polarizability tensors. The magnitude of the electrooptical effects depends on the effective electric field acting on the molecule. In preceding papers the representation of the effective field was based on the Onsager model. More recent experimental investigations have shown that this approximation is not sufficient when using polar solvents. Here, local fluctuations of the electric field have to be taken into account. Basing on previous theories, an extension including these effects is developed which agrees with the experimental results, as will be shown in the following paper7. Also, an approximate expression is derived for the mean square of the effective electric field
Photoionisation von Methanol und Formaldehyd / Photoionisation of Methanol and Formaldehyd
Authors: Warneck Peter
Published: February 2015

Photoions produced in methanol and formaldehyde by radiation in the spectral region 450 - 1150 Å were analyzed mass spectrometrically and their relative yields were determined as a function of wavelength. First ionisation potentials were determined and the ion yield curves were interpreted in terms of ionisation processes in conjunction with other data. Fragment ions were detected on mass numbers 31, 30, 29, 15, and 14 for methanol, and 29, 2, and 1 for formaldehyde. The associated appearence potentials were determined and were used to calculate heats of formation of the ions CH2OH+ and HCO+, and the radicals CH3, CH2, and HCO. The most important result appears to be the heat of formation found for HCO: ΔHB = 0.43 ± 0.07 eV, corresponding to 9.9 ± 1.6 kcal/mole, as well as the associated dissociation energies for HCO and formaldehyde. Previously existing discrepancies concerning these quantities are thereby clarified
Seif Diffusion in a Glassformer Melt Oxygen Transport in Boron Trioxide
Authors: Tokuda Taneki , Ito Tomoyasu , Yamaguchi Takashi
Published: February 2015

Quite a few investigations have been published on the diffusion of modifiers in glassy substances, but only a few studies have been reported on the self diffusion in a glassformer itself 1. The self diffusion of oxygen in a boron trioxide melt was measured in this study
A New Optical Method for the Determination of Interatomic Potentials
Authors: Behmenburg W.
Published: February 2015

A new method is described to obtain information on the true difference potential of interatomic interaction from the quasistatic wings of spectral lines broadened by neutral atoms. Based on the one-particle-approximation of the quasistatic theory of line broadening, it does not rely on any particular model function. Furthermore, from measurements of the temperature dependence of the line wings it may yield additional information on the potentials for the initial or final state of the line separately. The method is appplied to measurements of the red wing of the mercury absorption line 61S0 - 63P1 λ 2537 Å, perturbed by argon.
Thermodynamic Properties of Solid Systems AgCl + NaCl and AgBr + NaBr from Miscibility Gap Measurements
Authors: Sinistri Cesare , Riccardi Riccardo , Margheritis Chiara , Tittarelli Paolo
Published: February 2015

Miscibility gaps for the solid systems AgCl + NaCl and AgBr+NaBr have been measured by a high temperature X-ray technique.

For the two studied systems the solubility curves are very nearly symmetrical in respect to the compositions xNaCl = .513 and xNaBr = .506, while the upper critical temperature are 198 °C for AgCl + NaCl and 285 °C for AgBr+NaBr.

The thermodynamic properties of the two solid systems have been calculated using only experimental solubility data. Values of activity and of enthalpy of mixing were estimated and compared with those reported in literature.
Thermoluminescence of ZnS
Authors: Grasser R. , May A. , Scharmann A.
Published: February 2015

A number of zinc sulphide phosphors containing cobalt was prepared with various concentrations of additional impurities. Co++-ions in both copper and silver activated phosphors produce a characteristic glowcurve, showing three distinct peaks above liquid nitrogen temperature. It was established that the first and probably the second glowpeak is connected with distinct traps, while the third peak is caused by a continuous distribution of traps. Measurements of thermoluminescence spectra as well as investigations of energy storage capacity and temperature dependence of electron capture in traps pointed to a local association of traps and luminescence centres in the case of the first two glowpeaks, whereas electron transfer via the conduction band from traps to separated luminescence centers was assumed for the third peak. An already existing model was used for discussing the experimental results obtained.
Über die Ursache der Supraleitung. III / On the cause of superconductivity. III.
Authors: Krebs H.
Published: February 2015

By consideration of superconducting compounds, whose chemical bond nature is known or can be derived with some certainty, it is shown that superconductivity only occurs, if valency electrons of a band can move in at least one space direction without intersecting any nodal surfaces. This applies both for metallic substances and for semiconductors. The following examples are discussed:

1. Metallic and semiconducting compounds composed of elements of the main groups and having a lattice similar to that of NaCl.

2. Nb- and Ta-chalcogenides with MoS2-structure.

3. The clathrate-compound [Ag7O8]+X-.

4. LaC2 with CaC2-structure.

5. Metallic and semiconducting perovskites.

6. Spinels and interstitial compounds with NaCl-structure.

7. Pyrites.

8. Some metals and their alloys.

In the case of s-electrons, this condition is fulfilled for all space directions, in the case of <5-bonds only along the intersecting line of the two nodal planes. A “δ”-bond is often - especially in an NaCl-type lattice - associated with a translation perpendicular to this intersecting line (in the NaCl-type lattice a translation by a/2) and a rotation by 90°. In such a “δt”-bond system the four segments of a dt2g-electron belong to four adjacent canals of quadratic cross-section (in the NaCl-type lattice the side length is a/2) which are not intersected by nodal surfaces. Only electrons fulfilling the condition indicated above can be considered as “free electrons”.
On the Migration of Ions in Alkali Nitrate-Silver Nitrate Melts
Authors: Richter J. , Amkreutz E.
Published: February 2015

Stoichiometric transport numbers of the ion constituents of the molten salt mixtures NaNO3+AgNO3 and LiNO3 + AgNO3 (referred to the common anion) have been determined by EMF measurements in a concentration cell with transference. The composition range is 0.7 ≦ x ≦ 1.0 at 240 °C to 0.1 ≦ x ≦ 1.0 at 300 °C (x denotes the mole fraction of silver nitrate) in the system NaNO3 + AgNO3 , and 0.1 ≦ x ≦ 1.0 in the same temperature range in the system LiNO3 + AgNO3 , the phase diagram defining the lower limit and the decomposition of the melt the upper limit. In addition, ionic mobilities, conductivities, equivalent conductivities, and the characteristic quantities of the idealized melts of the two systems have been calculated at 260 °C and 290 °C.
The Isotope Effect for Electromigration of Sodium Ions in Molten Sodium Nitrate
Authors: Saito Nobufusa , Hirano Katsumi , Okuyama Kohei , Okada Isao
Published: February 2015

The relative difference (Δb/b) between the internal electromigration mobilities of 22Na and 24Na in molten NaNO3 has been measured in the range 340 - 515 °C. The internal mass effect, μint= (Δb/b)/(Δm/m) is - 0.056 at 340 °C (melting point 308 °C), - 0.079 at 435 °C and - 0.068 at 515 °C. The errors in μint are ±0.002.
Elektronendichte und chemische Verschiebung der Styryldiazin- und Diazaphenanthrenprotonen / Electrondensity and Proton Chemical Shift of Styryldiazines and Diazaphenanthrenes
Authors: Perkampus H.-H. , Bluhm Th. , Knop J.
Published: February 2015

Proton chemical shifts in styryldiazines and diazaphenanthrenes linearly correlate with SCF-π-electron densities of the attached carbon atom and with the electron densities of the hydrogen atom (calculated by the CNDO/2 method). The observed deviations from linearity are discussed in terms of ring current effect, steric effects and the paramagnetic effect of the nitrogen lone pair electrons. An appreciable weakening of ring current is found for diazaphenanthrenes with two adjacent N-atoms. Under the same condition the paramagnetic effect on ortho-hydrogens is increased.
Zur Beschreibung relativistischer Teilchen höheren Spins im elektromagnetischen Feld / The Description of Relativistic Particles with Arbitrary Spin in the Electromagnetic Field,
Authors: Ulrici Wolfgang
Published: February 2015

Starting with the equations of the center-of-mass motion and spin motion of a particle in a homogeneous electromagnetic field, we derive the Hamiltonian and the wave equation of a relativistic particle with arbitrary spin and arbitrary magnetic moment in this field. We change from the canonical representation to spinor representations with convenient transformation properties, and we find a form of the wave equation which, for the special case of spin 1/2, coincides with the Dirac equation (in the form first given by Feynman). The problems and limitations of this derivation are extensively discussed.
Notizen: Allox-Leiter zur elektrischen Serienschaltung von Hochtemperatur-Brennstoffzellen / All-ox Conductor for Series Connection of High-Temperature Fuel Cells
Authors: Kleinschmager H. , Reich A.
Published: February 2015

Lanthanchromit, dotiert mit Strontium und Nickel, sowie Lanthannickeloxid, dotiert mit Kobalt, ändern bei 1000 °C in einer Gasatmosphäre mit zwischen 1 - 10-16 atm variiertem O2-Partialdruck ihre spezifische elektrische Leitfähigkeit nur wenig, so daß diese Materialien gute Aussichten eröffnen, Einzelzellen ohne merkliche Leistungsverluste zu Hochtemperatur-Brennstoffzellen-Batterien zusammenzuschalten.
Notizen: Kinetic Theory of the Thermomagnetic Force
Authors: Hess S.
Published: February 2015

Results obtained within the framework of the kinetic theory of polyatomic gases, are reported for the influence of a magnetic field on the thermal force exerted on a solid sphere in a heat conducting gas.
On Determining the Sign of Fault Vectors by X-Ray Topography
Authors: Lang A.R.
Published: February 2015

Experiments show that the excess or deficiency of diffracted intensity in the image of the first fringe in stacking-fault-type fringe patterns on X-ray projection topographs can give a clear indication of the sign of the fault vector even when μ t is no greater than unity (μ is the normal linear absorption coefficient and t is the crystal thickness) provided that the crystal structure is such as will exhibit fairly strong anomalous transmission (Borrmann effect) in the thick crystal case for the Bragg reflections used. A quite simple diffraction theory suffices to account for the observations. Sign determinations based on this theory agree with those expected at Brazil twin boundaries parallel to major rhombohedral planes in quartz.
Polarization of the Recoil Proton for Proton Compton Scattering Below the Pion Production Threshold
Authors: Fengler H
Published: February 2015

The polarization of the recoil proton for Compton scattering on protons below the pion production threshold, which arises from fourth order Feynman diagrams, is calculated by using the second order Compton amplitude in the unitarity condition. It is assumed that the second order amplitude can be approximated by the one proton intermediate state contribution. The polarization does not exceed 0.1% in the entire range of the scattering angle.
Derivation of a Master Equation for Intramolecular Relaxation Using Projection Operator Techniques in Liouville Space
Authors: Rösch Notker
Published: February 2015

A generalized master equation is derived to describe intramolecular rearrangement processes. It is an inhomogeneous equation, including memory effects. The derivation is based on the Liouville space formalism. Because chemically relevant information is contained in the off-diagonal elements of the density matrix, a non-diagonal coarse-graining projector is used. All necessary assumptions are stated explicitly. By making further approximations, the master equation can be reduced to an inhomogeneous von Neumann equation with an effective Liouville operator the imaginary part of which is responsible for relaxation-like coarse-grained solutions. All neglected terms are given in closed form. The character of the solutions of the master equation is discussed in "coordinate-free" manner, i.e. without referring to the underlying Hilbert space.
Eine Approximation der Löwdinschen natürlichen Orbitale für Moleküle mit einer Green-Funktion-Methode
Authors: Albat R.
Published: February 2015

An Approximation of Löwdin's Natural Orbitals for Molecules with a Green's Function Method The many-body-pertubation theorie of the single-particle Green's function is used to get an approximate first-order density matrix. Slightly modified SCF-orbitals form the basis for the expansion. The mass-operator in Dyson's equation is considered up to second order in the Perturbation. In the present form the method is only applicable to ground states with closed shells. The ground states of the molecules LiH and NH3 serve as examples to demonstrate the usefulness of the directly calculated natural orbitals for application in the C I-method. The natural orbitals give a much better convergence of the C I-expansion than the SCF-orbitals do.
Mössbauer-Effekt am Fe57 in Additions-und Substitutionsverbindungen des Natrium-Nitrosylprussiates / Mössbauer-Effect in Fe57 of Addition and Substitution Compounds of Sodium Nitroprusside
Authors: Weihofen Ulrich
Published: February 2015

Investigating 21 iron complex compounds of the type [Fe(CN)5NOL]n- or [Fe(CN)5L]3- it was found that isomeric shift, quadrupol splitting, and Goldanskii effect depend on the purity of the compound. Varying the amount of impurity discrepancies between formerly published data could be explained. The Mössbauer spectra of three compounds showed line widths differing from the theoretical value only by a few per cent. This indicated that a very high purity had been achieved. In all cases information about the molecular structure and the bond strength between the central Fe-atom and its ligands was obtained.
Parametric Study of Functions of Molecular Vibrations
Authors: Alix A. , Bernard L.
Published: February 2015

In this work, the authors give the parametric form of the Zeta constants for the case of the molecules XY2 and X3 (symmetric species C2v), as a function of the mathematical parameter a which generates all the solutions, and of the molecular coupling coefficient Ψ12 between two symmetry coordinates S1(A1) and S2(A1).
Hyperfeinstruktur Des Csbr
Authors: Hoeft J. , Tiemann E. , Törring T.
Published: February 2015

The quadrupole hyperfine structure of 133Cs 79Br was measured on the rotational transition l=1 → 2 at 4.3 GHz. The obtained quadrupole coupling constants of 79Br in various vibrational states are reported.
Circular Polarization of Gamma Rays and Parity Nonconserving Interactions
Authors: Dumitrescu O. , Gari M , Kümmel H , Zabolitzky J. G.
Published: February 2015

An explicit expression for the circular polarization of gamma rays emitted by odd mass deformed nuclei is given. A semi-microscopic description of the nuclear excited states based on pairing plus quadrupole and octupole model is used. The average field is based on a deformed diffuse edge potential. The short-range correlations are taken into account via the generalized Bethe-Goldstone-equation.
Elektronen-Spin-Resonanz und ENDOR-Messungen an Fe3+ und Cr3+ in Zinndioxid
Authors: Rhein W
Published: February 2015

ESR measurements on Fe3+ and Cr3+ at interstitial sites in SnO2 show that two of the magnetic main axes form an angle of 0.7° to the crystallographic axes. Additional information as to which kind of sites are occupied is yielded by ENDOR measurements of the Fe57, Cr53 hyperfine inter-action, and of the superhyperfine interaction with neighbouring Sn-ligands. It is, furthermore, shown that hydrogen is present in the immediate surroundings of both 3d-ions at interstitial sites
Einige Bemerkungen über die Erzeugung von elektromagnetischen Wanderwellen und stehenden Wellen zur induktiven Plasmabeschleunigung
Authors: Meert A
Published: February 2015

Some comments are made for the generation of e.m. travelling and standing waves used for in-ductive plasma acceleration. Resulting from a simple mathematical formulation the different features lead to a non-conventional method for travelling wave generation, which is compared with the basic method - i. e. the standing wave generation - with regard to Ohmic losses and mag-netic energy density
Relaxation Phenomena in the Biological Carbon Cycle under Conditions of Variable Atmospheric CO2 -Content
Authors: Wagener K , Forstel H
Published: February 2015

Under normal conditions the carbon cycle is a stationary process. A varying CO2 partial pres-sure would cause deviations from the steady state. This process is analysed using a differen-tiated flow scheme of the carbon through the biosphere. For this purpose the biomass on land is divided into three reservoirs with average fixation times of 1 day (day-night-cycle), 2 years (annual period), and 100 years (timber, humus), respectively. The kinetic analysis shows that about 70% of the global respiration follow fluctuations of the rate of photosynthesis immediately, so that this portion of the excess of fixed carbon will be returned in the atmosphere within a few years. Only 30% of the total cycle passes through the largest reservoir (timber, humus) which could serve as a buffering system. But since the time constant of this partial cycle is about 100 years, the CO2 exchange with the ocean is the faster process
Protonenrelaxation und dynamische Kernpolarisation in Metall-Ammoniaklösungen
Authors: Mehner A.-W , Müller-Warmuth W
Published: February 2015

Relaxation times and Overhauser enhancements for protons in metal (K, Li, Na, Ca) ammonia solutions have been measured at 176, 3400 and 11 200 G over a wide range of concentrations and temperatures. Both the relaxation rate due to the interaction with unpaired electrons and the Overhauser coupling parameter are strongly frequency-dependent and undergo a characteristic change at metal concentrations of 0.05 - 0.5 M. They can be explained by a mixed scalar and di-polar coupling. Coupling amplitudes, spectral intensity functions and correlation times with their temperature-dependence have been determined. The results and a comparison with Knight shift data show that more than one paramagnetic species in the solution, and different mechanisms of relative motion between protons and electrons must contribute. The major part of the coupling is of a short range type, where the electrons, by some kind of tunneling, are the carriers of the motion. The discussion postulates dissolved electrons with rather flexible solvation spheres where spin density is greatly smeared out. The second paramagnetic species may be the "monomer" often dis-cussed in the literature. Additional experiments which support our conclusions have concerned the self diffusion coefficient of the protons, and the Overhauser enhancement of lithium-7
Zur nukleon-nukleon-s-streuung. Ii. der numerische stabilitätstest / On nucleon-nucleon s-scattering. ii. the numerical stability test
Authors: Drumm H , Trübenbacher E
Published: February 2015

On Nucleon-Nucleon S-Scattering. II. The Numerical Stability Test The numerical stability test is discussed which prevented the decision on the usefulness of a non-relativistic nucleon-nucleon potential of a previous paper, and this decision is finally accomplished by fulfilling the stability condition
Die bildung unsymmetrischer excimerer zwischen pyren und 4.5-iminophenanthren / Pyrene and 4.5-iminophenanthrene form unsymmetrical excimers in cyclohexane solutions
Authors: Steidl H. , Hoffmann G.
Published: February 2015

Aromaten bilden mit einigen ihrer Derivate unsym- metrische Excimere1. Ob unsymmetrische Excimere auch zwischen dem aromatischen Pyren (I) und dem heteroaromatischen, zu Pyren isoelektronischen 4.5- Iminophenanthren (II) gebildet werden, soil hier un- tersucht werden. Da beide Molekiile nahezu gleiche Elektronenanregungszustande haben2, jeweils sym- metrische Excimere bilden 1,3 und (II) 4 ebenfalls wie (I) ein planares Molekiil ist, erscheint es naheliegend, die Bildung unsymmetrischer Excimerer zwischen (I) und (II) zu erwarten. Abbildung 1 zeigt die Struktur- formeln beider Molekiile
The Ground State Energy of the Hubbard Model in Hubbard's Approximation
Authors: Jelitto Rainer
Published: February 2015

We have calculated the ground state energy of the Hubbard model in the approximation of Hubbard's first paper1 . For the neutral model with nearest neighbour interaction the energy resulting from the selfconsistent paramagnetic solution is compared with those ones following from the (ferromagnetic) Hartree-Fock and an (antiferromagnetic) single particle theory. The energy of the latter one turns out to be the best approximation of the true ground state energy of the model for all values of the coupling constant V0 , but the energy derived from Hubbard's approximation, in spite of the absence of magnetic ordering, is a reasonable approximation at least for sufficiently large values of V0.
Elastic Constants of Nematic Liquid Crystals
Authors: Gruler Hans , Scheffer Terry J. , Meier Gerhard
Published: February 2015

We present a theoretical treatment and give experimental observations of the deformation that occurs in a nematic liquid crystal when electric or magnetic fields are applied. We consider only normal deformations in the nematic material where fluid flow and other dynamic phenomena play no role. Three important sample geometries are considered in the magnetic field, and the experimentally observed deformations are in good agreement with theory. The normal deformation induced by electric fields is of interest from a device standpoint, and we give a solution for the deformation that is valid even for large dielectric anisotropics. This solution has been experimentally verified. We give a detailed comparison of the distortions produced by electric and magnetic fields and show that the deformations are of a similar form even though the field is nonuniform in the electric case. The change in birefringence and electrical capacitance as a function of distortion is discussed as a means of observing the deformation.
Microwave Spectrum and Quadrupole Coupling Constants of Orthochloropyridine
Authors: Scappini F , Guarnieri A
Published: February 2015

The rotational spectrum of 2-chloropyridine was measured in the region between 8-40 GHz. The rotational constants for the vibrational ground state are:

A = 5872.01 ± 0.02 MHz, B = 1637.82 ± 0.02 MHz, C=1280.51 ± 0.02 MHz.

The value 0.0385 amu · A2 of the inertia defect indicates a planar nuclear frame. From the hyper-fine splittings of the rotational lines the nuclear quadrupole coupling constants of 35Cl were determined. The values are:

χaa = 70.79 ± 0.17 MHz, χbb = 39.01 ± 0.45 MHz, χcc = 31.78 ± 0.62 MHz.
Notizen: Empirical Evidence for Shell Effects in (n,p)- and (n,α)-Reaction Cross Sections Induced By 14 Mev Neutrons
Authors: Holmberg P.
Published: February 2015

Cross section values for (n,p)-and (n,α)-reactions have been analysed as functions of the proton and neutron numbers of the target nuclei. When these numbers equal or approach those of a closed shell structure, the cross section values tend to increase. Far from closed shells the cross sections are small.
Elastische und thermoelastische Konstanten des LiBaF3 / Elastic and Thermoelastic Constants of LiBaF3
Authors: Haussühl S. , Leckebusch R. , Recker K.
Published: February 2015

The elastic and thermoelastic constants of cubic LiBaF3 are measured by ultrasonic methods. As a consequence of the larger packing density which results from the higher coordination number of the Ba ions in LiBaF3 the values for the mean elastic stiffness and for the refractive index exceed those of LiF and BaF2 . A quantitative explanation of these properties is given. The values of many other properties range between those of LiF and BaF2.