bluuebunny/crossref_metadata_2025 huggingface dataset:
Dynamische Kernpolarisation in Lösungen von freien Radikalen in substituierten Pentafluorbenzolen / Dynamic nuclear polarisation in solutions of free radicals in substituted pentafluorobenzenes
Authors: Yalçiner Aytaç
Published: February 2015

Intermolecular scalar hyperfine coupling between unpaired electron orbitals and 19F nuclei has been studied in solutions of free radicals in substituted pentafluorobenzenes. Dynamic nuclear polarisation experiments in a weak magnetic field and at various temperatures have shown that both the strength of the intermolecular interaction and the range, depend sensitively upon the π-electron distribution of the aromatic system. The amount of scalar coupling increases with substitution in the sequence H, CH3 , J, Br, CI, F, CN and with the kind of radicals in the order TTBP, DPPH and BDPA.
Mikrowellenspektrum, Rotationskonstanten, Kernquadrupolkopplungskonstanten und r0-Struktur von Äthylchlorsilan / Microwave Spectrum, Rotational Constants, Nuclear Quadrupol Coupling Constants and ro structure of Ethylchlorosilane
Authors: Typke V. , Dakkouri M. , Zeil W.
Published: February 2015

The MW-spectra of trans- and gauche-rotamers of 5 isotopes of ethylchlorosilane have been measured and partially analyzed. From the analysis rotational constants, centrifugal distortion constants and nuclear quadrupol coupling constants have been obtained. The determination of the restructure from 30 rotational constants leads to different bond angles C -C -Si for the two conformers. The optimalization of the quadrupol coupling constants in the bond axis system on the basis of the r0-structure using all information on the 35Cl-species yields the following values: ZZZ = (-35.5±0.8) MHz, η = - 0.25±0.11 for the trans-form and ZZZ= (-36.3±2.7) MHz, η = -0.08±0.10 for the gauche-form.
Possible Nuclear Structure Effects in Even-Even Osmium Nuclei
Authors: Bashandy E. , El-Nesr M. S.
Published: February 2015

A compilation of the multipole mixing of 2′ + → 2 + transitions in 186Os, 188Os, 190Os and 192Os is given. In view of recent results obtained at our laboratory, indicating large anomalies in the conversion process of inhibited M1 transitions, the study has been extended for even-even Osmium nuclei. A series of experiments has been performed in which the conversion coefficients and transition probabilities were measured. The data of 2′ + → 2 + transitions were analysed by taking into account nuclear structure effects on the Ml internal conversion process. The M1 admixtures obtained are compared with Greiner′s calculations. Values of reduced transition probabilities B (E2, 0 → 2 +) , B (E2, 2′+ → 2+) , the mixing ratio δ = 〈2 || E2 || 2′〉 / 〈2 || M1 || 2′〉 and the transition branching ratio T (2′ → 2)/T(2′ → 0) are reported for second and higher 2+ states. The results are compared to the pairing-plus-quadrupole model calculations of Kumar and Baranger.
Scattering of Ions VI. Elastic Scattering of N+ on Ne, Ar, Kr, and Xe
Authors: Weise H.-P. , Mittmann H.-U.
Published: February 2015

In the elastic differential cross-section of the N+-rare gas systems two different types of oscillations have been observed. At an energy of a few eV a primary rainbow was detected for all systems. In the case of N+ - Ar, secondary rainbows were resolved too. From these experimental data the potential depths were determined to be: ε (N+ - Ne) = 0.4 eV, ε (N+ - Kr) = 0.29 eV, ε

(N+ - Xe) = 0.92 eV. For the system N+ - Ar the shape of the reduced potential was obtained by evaluating the positions of the secondary rainbow extrema. The potential depth was found to be 2.16 eV. At higher energies and large scattering angles additional oscillations appeared which are presumed to be Stueckelberg oscillations. For N+ - Ne a single group of strongly marked oscillations appeared up to the highest energies used (EL = 220 eV). In the case of N+ - Ar the amplitudes of these undulations are strongly quenched. For N+ - Kr and N+ - Xe several groups of oscillations with different amplitudes and frequencies seem to be superimposed in the differential cross-section. They are attributed for all systems to crossings of the incoming state with the charge exchanged state.
Interionic Potentials for Some Alkali Halides from Crystal Data Measured at Different Temperatures
Authors: Romano Silvano , Margheritis Chiara , Sinistri Cesare
Published: February 2015

Values at different temperatures of lattice constants and their derivatives with respect to T. and of elastic constants were used to obtain the derivatives with respect to the minimum interionic distance of the repulsive potentials for the crystals CsCl, CsBr, ClI, NaCl, KCl and KBr. The derivatives thus calculated were then subjected to a computer fitting to yield the aij and b constants of the interionic repulsive pair potential: Rφij = aij exp{ - brij}.
Oberflächenpolaritonen zweiachsiger Kristalle mit Plattenform / Surface Polaritons of Biaxial Crystals in the Slab Configuration
Authors: Borstel G.
Published: February 2015

Fano type surface polaritons in biaxial crystal plates are discussed. The dispersion relation for Fano modes is derived and has been evaluated for an a-quartz slab with regard to real and virtual extraordinary surface modes.
Untersuchungen zur Keimbildung von Gold auf Kohlenstoffschichten / Investigations to the Nucleation of Gold on Carbon Layers
Authors: Paunov M. , Harsdorff M.
Published: February 2015

In the present paper, the nucleation of gold on thin carbon layers is investigated. By means of an image analysing computer it was possible to evaluate many electron micrographs with regard to nucleation rate, growth of crystallites, induction time and fractional part of the surface covered by crystallites. The comparison of the experimental results with nucleation theories shows that the explanation is possible by use of a simple atomic model.
Molecular Structure, Quadrupole Coupling Tensor and Dipole Moment of Ethyl Cyanide
Authors: Heise H. M. , Lutz H. , Dreizler H.
Published: February 2015

The microwave spectra of CD3CH2CN, 13CH3CH2CN, CH3
13CH2CN and CH3CH2C15N have been measured. In addition the spectrum of CH3CH2
13CN has been remeasured with greater accuracy. From these spectra and those previously reported - CH3CH2CN, CH3CD2CN, CH2DCH2CN (sym) and CH2DCH2CN (asym) - a complete rs-structure has been calculated by the equations of Kraitchman and Chutjian. r0-structure calculations were performed with different assumptions due to the symmetry of the molecule. A comparison between r0- and rs-structure was made and showed good agreement especially for the atoms of the frame.

The quadrupole coupling constants of the above mentioned isotopes of ethyl cyanide were obtained from the hyperfine structure of the spectra with the exception of CH3CH2C15N, which has no nucleus with quadrupole moment. The quadrupole coupling tensor in its principal axis system was determined from the constants of CD3CH2CN and CH3CD2CN using the angle e between their principal axes of inertia in the a-b-plane.

From Stark effect measurements the dipole moment of CH3CH2CN was reevaluated. To determine the direction of the dipole moment Stark effect measurements for CD3CH2CN and CH3CD2CN were carried out.
Electronic Spectra and Conformations of Some Heterocyclic Derivatives of 5H-Dibenzo(a,d)cycloheptene
Authors: Tóth T. , Klasinc L.
Published: February 2015

The electronic transitions in 5H-dibenzo (a,d)-cycloheptene (1), 5H-dibenz(b,f)azepine (2), dibenz( b,f)oxepine (3), 5-dibenzo(a,d)cyclohepten-5-one (4), dibenzo(b,f)thiepine (5) and dibenzo (b,f) selenepine (6) have been calculated by the SCF LCAO MO CI method for model conformations and compared with experimental uv absorption spectra. The spectral characteristics and conformations of the title compounds and their relationship to cis-stilbene and o-substituted cis-stilbenes are discussed.
On the Definitions of Characteristic Molecular Vibrations and the Distribution of Vibrational Energy
Authors: Alix Alain J. P. , Freeman Daryl E. , Müller Achim
Published: February 2015

The relationship of the definition of a completely characteristic normal vibration to the stationary properties of force and compliance constants is examined. The corresponding properties of various distributions of potential, kinetic, and total vibrational energy are described.
Einfluß der Strömungsform des Gases auf die chemischen Transportprozesse in Halogenglühlampen
Authors: Neumann Gerhard M.
Published: February 2015

By raising the inert gas pressure and thus changing the type of gas flow chemical transport processes in tubular halogen incandescent lamps may be influenced. At medium pressures in the region of laminar flow separation of halogen and inert gas due to thermodiffusion occurs, the halogen cycle breaks down, and bulb blackening of the lamp is observed. At low and high pressure, where the streaming behaviour of the gas phase is dominated by diffusion or turbulence, separation of halogen and inert gas is overcome and the lamps stay clean. Observed pressures for changing from laminar to turbulent flow are 3.5 atm in xenon, 5.5 atm in krypton, and > 8 atm in argon in good accord with the well-known Reynolds' criterion.
Reflection of Ionized Hydrogen Clusters at Polished Stainless Steel
Authors: Gspann J. , Krieg G.
Published: February 2015

Ionized hydrogen clusters of either charge polarity containing some 105 molecules of hydrogen can be reflected at a polished stainless steel surface, for purposes of fusion fuel injection, very similarly to neutral clusters. The effective charge of positive cluster ions increases by a factor of about 1.5 during the reflection.
Anomalie der elektrischen Leitfähigkeitsanisotropie von 4,4' -Di-n-hexyloxy-azoxybenzol
Authors: Heppke G. , Schneider F.
Published: February 2015

The electric conductivity of 4,4'-di-n-hexyloxyazoxybenzene is studied as a function of temperature for parallel and perpendicular alignment. Below the clearing temperature the ratio of anisotropy V=x||/x⟂ is found to be higher than unity. Its value decreases below unity when approaching the transition to the smectic phase. Increasing the concentration of the electrolyte tetrabutylammonium picrate yields an unexpected increase of the ratio of anisotropy.
Calculations of the Oxygen Isotope Fractionation between Hydration Water of Cations and Free Water
Authors: Bopp P. , Heinzinger K. , Vogel P. C.
Published: February 2015

The oxygen isotope fractionation factors between the hydration complex of the alkali ions in the gas phase and a free water molecule have been computed on the basis of the energy surfaces calculated by Kistenmacher, Popkie and Clementi for a water molecule in the field of an alkali ion. For comparison with recently measured oxygen isotope fractionation factors in aqueous alkali halide solutions, the gas phase values are multiplied with the corresponding separation factors between water vapor and liquid water thus relating the hydration complex in the gas phase with pure water. Qualitative agreement between computed and observed fractionation factors has been found for H2O and D2O even neglecting the isotope effect connected with the transfer of the hydration complex from the gas phase to the solution. This transfer effect is estimated for H2O by a quantitative comparison of computed and observed oxygen isotope fractionation factors.
Electrical Conduction in Narrow Energy Bands
Authors: Marsch E. , Steeb W.-H.
Published: February 2015

The electrical conductivity of the single-band Hubbard Hamiltonian is calculated by use of the Boltzmann-Transport-Equation. We lean on the antiferromagnetic approach to this Hamiltonian. We obtain a semiconductor with an energy gap due to the electronic correlations and a semiconductor to metal transition at the Néel temperature TN.
Mo-theoretische Versuche zur Vorhersage der unterschiedlichen chemischen Verschiebungen von E- und Z-Oximen / MO Theoretical Attempt for the Calculation of the Different 13C Shifts of E- and Z-oximes
Authors: Sterk H. , Steininger H.
Published: February 2015

An attempt is made calculate the 13C-shifts of E- and Z-Oximes from their σDia- and σpara- shift term. The charge densities used in the shift terms are calculated by the CNDO/II-method. The theoretical assignment is verified by measuring the pseudocontact-shift of the E- and Z-Oxime with Pr (fod)3-d27.
Boundary Condition for the Distribution Function of a Gas of Linear Molecules
Authors: Halbritter J.
Published: February 2015

The scattering of linear molecules by a potential wall is studied. It is assumed that the interaction potential between the molecule and the wall depends on the distance of the center of mass of the molecule from the wall and on the orientation of the molecular axis. From the wave function of the reflected molecule an expression for the transition probability for scattering into the various final molecular states is obtained. Together with a modification of Maxwell's assumption for the interaction of atoms with solid surfaces, this transition probability is used to derive a boundary condition for the distribution function of a gas of linear rotating molecules. This also takes into account the change of rotational angular momentum in the collision with the wall.
Isothermal Diffusion and Trapping of Helium in a Silver-Lithium-Alloy after Neutron Irradiation
Authors: Gaus H. , Migge H. , Mirus K.-D.
Published: February 2015

The release of helium from neutron-irradiated Ag-9.6 at.-% Li-alloy is measured in the range between 510 and 784 °C. Analytical expressions are developed taking into account a recoil modified concentration profile in a surface layer. The isothermal kinetics can be described to some extent with two parameters, the effective diffusion coefficient p2D and the absorption coefficient μ of helium in traps. From foil-experiments the untrapped fraction p of gas after irradiation is found to be 0.2 ≦ p ≦ 1 for a helium concentration of 1.1·10-5 at.-%. The activation energy of diffusion is found to be 1.7 eV, which indicates a vacancy mechanism. The absorption coefficient μ is of the order of some 10-4 [sec-1] and nearly independent of temperature. It is discussed whether the diffusion to the traps or the capture process itself with a negative activation entropy is rate determining. The method seems to be applicable to incomplete degassing of other gas-metal-systems described in the literature.
Mössbauer Effect Studies of Europium-151 Complexes
Authors: Kumar S. , Rao G. N. , Medhi O. K. , Agarwala U.
Published: February 2015

The Mössbauer effect in a number of europium (III) complexes with ligands having nitrogen or oxygen as donor atoms has been studied at room temperature. A comparison of the resonance effects indicates significant differences between several of the complexes. High resonance effects are correlated with the polymeric nature of the complexes. The isomer shifts of the complexes have also been interpreted on the basis of the participation of 6s or/and 4f or 5p orbitals in the bond formation.
Elektrochemische Untersuchung der chemischen Diffusion in Wüstit mit Hilfe eines oxidischen Festelektrolyten/ Electrochemical Investigation of Chemical Diffusion in Wüstite Using a Solid Oxide Electrolyte
Authors: Rickert H. , Weppner W.
Published: February 2015

Chemical diffusion measurements in wüstite were carried out with the help of the solid state galvanic cell

pO₂, Ptl |ZrO2(+Y2O3)| Fe1 - δ(ϰ)O| Pt2, N2

with doped ZrO2 as a solid electrolyte which exhibits practically pure conduction for oxygen ions. Starting from an initial homogeneous stoichiometry as given by δ, the voltage E of the cell, i. e. the chemical potential of oxygen (or δ) in Fe1 - δO at the phase boundary with the electrolyte, was changed in small steps, corresponding to 3,5 - 15% of the whole stoichiometric range. The re-equilibration of the compound was observed by the current as a function of time. Alternatively, a small constant current was applied to the galvanic cell and the voltage between the wüstite and a reference electrode was measured. From the relaxation behaviour the chemical diffusion coefficient can be determined in several ways. The values are consistent with those calculated from tracer diffusion coefficients, the thermodynamic factor, which could be estimated from coulometric titration measurements, and a correlation factor of the order of 1. In contradiction to previous results with thermogravimetric methods the chemical diffusion coefficient increases with growing deviation from the ideal stoichiometry.
Zur Konvergenz der numerischen Berechnung von Energieeigenwerten mit Hilfe der Wegintegralmethode / On the Convergency oj the Numerical Calculations of Eigenvalues with the Method oj Path Integrals
Authors: Freudenhammer A. , Simon G.
Published: February 2015

A method is presented which permits computation of the spectra of hamiltonians with special potentials. This method uses path integrals for the evaluation of Feynman-propagators and is a generalization of Evseev's method. It is shown that, depending on the form of the potential, expansions of series occur which can be summed up according to criteria of convergency for divergent series, i. e. Cesàro- or Euler-summability. Consequently interchanging of summation and integration is not allowed for all regions of the complex time plane. This is shown explicitly for the 6-dimensional harmonic oscillator.
Die elektrischen Transporteigenschaften von p- und n-Cd1-ϰ Znϰ Sb für 0≦ ϰ≦ 0,5 / The Electrical Transport Properties of p- and n-Cd1-ϰZnϰSb for 0≦ϰ≦0,5
Authors: Lehnefinke W.
Published: February 2015

The temperature dependence of electrical resistance, Hall coefficient, and thermoelectric power has been investigated in the temperature range from 10 K to room temperature. Undoped mixed crystals of the semiconducting compounds CdSb and ZnSb show p-type conduction in the whole temperature range. To get the n-type, samples of the composition Cd1-ϰZnϰSb with 0≦ϰ≦0,5 were doped with Se and Te. All Te-doped specimens show n-type conduction. In Se-doped samples n-conduction is achieved only for ϰ = 0 and ϰ = 0.1. Some of the doped samples change to p-type conduction at lower temperatures between 130 K and 210 k. In the region of the lowest measured temperatures a second sign change occurs to negative values again. A special treatment of the samples shows that this anomalous behavior is strongly affected by surface effects. By using a simple model for the structure of the samples these effects were explained.
Normal Coordinate Analysis and Mean Amplitudes of Vibration of Spiropentane
Authors: Cyvin B. N. , Gebhardt O.
Published: February 2015

Using spectroscopic data and structure parameters observed by electron diffraction, a normal coordinate analysis was performed for spiropentane. Harmonic force field, potential energy distribution and calculated mean amplitudes of vibration are reported. A very satisfactory agreement is found between observed and calculated mean amplitudes of vibration.
Studies on the PMR Spectra of Oxetanes. VI 2-(3-Chlorophenyl)oxetane and 2-(2-Chlorophenyl)oxetane at 60 and 100 MHz
Authors: Jokisaari Jukka
Published: February 2015

The 100 MHz spectra of the phenyl protons in 2-(3-chlorophenyl) oxetane and 2-(2-chlorophenyl) oxetane have been analysed. The 60 MHz PMR chemical shifts and proton-proton coupling constants have been studied in the temperature range from -20 C to +80 °C. The chemical shifts were sensitive to temperature, while the coupling constants were not, except the long range 5Jm coupling constant between the methine proton and the meta positioned phenyl proton in 2-(2-chlorophenyl) oxetane.
Thermodiffusionsfaktor von n-Heptan—Benzol mit einer Autokollimationsmethode / The Thermal Diffusion Factor of n-Heptane — Benzene
Authors: Korsching H.
Published: February 2015

The concentration-dependence of the thermal diffusion factor α is determined in the binary system n-heptane - benzene at 25 °C. α ranges from 0.72 to 2.39 for the mole fraction of benzene going from 0.1 to 0.9. By the aid of a mirror the sensing light beam passes the cell twofold, which results in a corresponding higher sensitivity.
Thermal Diffusion in Some Binary Liquid Mixtures by the Flowing Cell Method
Authors: Poty P. , Legros J. C. , Thomaes G.
Published: February 2015

In this paper we present measurements of the Soret coefficient (D'/D) by means of a flowing cell technique for disulfide- 3 methylpentane and for the three associated solutions: carbon tetrachloride-ethanol, carbon tetrachloride-isopropanol and water-isopropanol.
On the Electron Affinities of Halogens and the Strength of Ionic Interactions
Authors: Hooydonk G. Van
Published: February 2015

A new interpretation is forwarded for the enthalpies of ionic interactions ⊿HAB. From observed trends in ⊿HAB values for alkalisalt molecules, it is concluded that the electron affinities of halogens are in need of revision.
Diffusionsgrenzstrom und verwandte Probleme bei Elektrolytschmelzen mit drei ionischen Bestandteilen / Limiting Diffusion Current and Related Problems of Ionic Melts with Three Ion Constituents
Authors: Haase R.
Published: February 2015

Starting from the general equation for the simultaneous occurrence of electromigration and diffusion in an ionic melt with three ion constituents, we derive the rigorous expression for the electric flux at an electrode interface. This expression contains the ratio of the interdiffusion coefficient of the melt to the internal transport number of the ion constituent that does not cross the interface. In the case of the limiting diffusion current (occurring in the problem of diffusion overvoltage), the electric flux contains the limiting value for infinite dilution of the interdiffusion coefficient.
A New Relation between Dissociation Energy and Molecular Constants of Diatomic Molecules
Authors: Bhutra M. P. , Tandon S. P. , Vaishnava P. P.
Published: February 2015

An accurate relation, connecting dissociation energy D0, force constant for infinitesimal amplitude ke and internuclear equilibrium distance re has been deduced from Varshni and Shukla's potential function. It is of the form D0=ke {A + B re
2 + C re
4), where A, B and C are constants and are the same for groups of similar diatomic molecules. The values of D0 estimated by this relation are in better agreement with the observed ones than those estimated by Somayajulu, and Tandon et al.
Electronic Density of States of Noncrystalline Si and Ge: I. Spherically Symmetric Interference Function Approach
Authors: Haider N. C. , Wourms R. L.
Published: February 2015

The electronic density of states have been calculated for amorphous and liquid phases of Si and Ge, using pseudopotential perturbation theory. These calculations are carried out on the basis of experimental radial distribution functions for the appropriate phases, and second order in electron energy. The density of states generated by this method compare favorably with those obtained by other computational methods.
Dielectric Constants and Molecular Structure of Nematic Liquid CrystalsII. Variation of the Bridging Group
Authors: Jeu W. H. de , Lathouwers Th. W.
Published: February 2015

Measurements are presented of the dielectric constants of some nematic compounds with the structure

The following bridging groups X are considered: C ≡ C, CH = CH, CCl = CH, N = N, CH = N, N = CH, CO - O and O -CO. Starting from the compounds with non-polar bridging groups the influence of the group X on the dielectric properties is systematically evaluated.
Condensation and Evaporation of a Dilute Vapour on a Spherical Droplet
Authors: Williams M. M. R.
Published: February 2015

The behaviour of a dilute vapour, diffusing in a non-condensable gas, has been investigated. The vapour condenses on, and evaporates from, a spherical droplet, and the appropriate Boltzmann equation has been formulated thus enabling the condensation rate to be calculated in a precise manner. In contrast to previous work on this problem, the saturation temperature of the droplet differs from that of the non-condensable gas and this leads to certain differences and difficulties in the calculations. Despite these difficulties, an approximate method has been developed which uses the integral form of the transport equation to express the condensation rate in a form which includes any type of vapour-gas interaction. This is an advance on previous work which was confined to simple model problems and restricted to isotropic scattering. An expression for the heat flux to the droplet is obtained and a method for calculating the vapour density and temperature is outlined. Finally, we stress the limitations of the method and suggest ways in which these may be overcome.
Stark Broadening of A III and AIV Lines
Authors: Platiša M. , Popović M. , Dimitrijević M. , Konjević N.
Published: February 2015

The half-widths of five A III and two A IV lines have been measured in a pulsed arc operated in an argon-nitrogen mixture. Electron densities of 3.8 to 8.0 × 10 16 cm-3 were determined by laser interferometry at a single wavelength while electron temperatures from 20750° to 23100 °K were measured from the relative intensities of All lines. The experimental A III and A IV Stark profile halfwidths were compared with calculated values using various theoretical approximations.
Isotopeneffekt und Druckkoeffizient der Übergangstemperatur zur Supraleitung in der Eliashberg-Theorie / Isotope Effect and Pressure Coefficient of the Superconducting Transition Temperature within the Eliashberg-Theory
Authors: Kessel W.
Published: February 2015

Isotope Effect and Pressure Coefficient of the Superconducting Transition Temperature within the Eliashberg-Theory Starting from the observation that both the mass of the ions and their volume control the phonon frequencies by stretching the phonon spectrum, the change of the Eliashberg-equations of the theory of superconductivity regarding these stretchings is considered. General expressions for the isotopic exponent and the pressure coefficient of the transition temperature are derived in which only derivatives of the transition temperature with respect to the fundamental parameters of the theory are involved. A comparison with experimental values shows that lead is not the metal with the highest transition temperature possible under the simple metals.
Konzentrations-und Temperaturabhängigkeit der Sensibilisierten Verzögerten Fluoreszenz in Naphthalin/Anthracen-Mischkristallen / Sensitized Delayed Fluorescence in Naphthalene/Anthracene Mixed Crystals: Concentration and Temperature Dependence
Authors: Port H. , Bader M. , Weber G. , Wolf H. C.
Published: February 2015

The delayed fluorescence of naphthalene crystals doped with anthracene has been investigated for concentrations between 7 × 10-9 and 10-5mol/mol in the temperature range 4.2 -300 °K. The concentration dependence of both the quantum ratio of host and guest emission and of the lifetime shows the effectivity of energy transfer by triplet excitons. It can be described quantitatively within the statistical hopping model, which includes the probability for an exciton to visit the same host molecules repetitively before becoming trapped. This incoherent energy transport becomes faster as the temperature is lowered. The exciton hopping time decreases monotonically from tʜ = 2 × 10-10 sec at 300 °K to tʜ = 8 × 10-11 sec at 130 °K. Below 100 °K the delayed fluorescence is governed by competing trapping effects.
The Electric Conductivity of Molten HgI2 -HgBr2 and Hgl2 -Sbl3 Binary Mixtures
Authors: Mentus S. V. , Šušić M. V.
Published: February 2015

The specific electric conductivity of molten HgI2-HgBr2 and HgI2-SbI3 binary mixtures was measured as a function of composition and temperature in the ranges 220 - 540 °C and 180 to 540 °C, respectively. In the HgI2-HgBr2 system negative deviations from additivity are found in mixtures rich in HgBr2, and positive ones in those rich in HgI2. The positive deviations are more pronounced at higher temperatures. In the HgI2-SbI3 system the deviations from additivity are negative throughout.
Untersuchungen der elektrischen Leitfähigkeit homologer 4,4′-Di-n-alkyloxy-azoxybenzole im nematischen Phasenbereich / Investigation of the Electric Conductivity of Homologous 4,4′-Di-n-alkoxyazoxybenzenes in their Nematic Phase
Authors: Heppke G. , Schneider F.
Published: February 2015

The effect of temperature and concentration of the added electrolyte tetrabutylammoniumpicrate on the electric conductivity of homologous 4,4′-di-n-alkoxyazoxybenzenes (C1 to C8) in their nematic phase is investigated. In general an increase of the alkyl chain length results in a decrease of the ratio of anisotropy x∥/x⊥. At the lowest temperature of the nematic phase values between 1,6 (C2) and 0,45 (C8) are obtained. This behaviour can be explained by the formation of cybotactic groups with a smectic structure. Increasing the electrolyte concentration reduces the ratio of anisotropy for short alkyl chains, whereas for long chains the ratio rapidly increases.
Detection of Nitric Oxide by the Resonance Absorption Technique
Authors: Meinel H.
Published: February 2015

The resonance absorption method is described for detecting ppm concentrations of NO mixed with other gases. As source lamp for the emission of the NO γ system, A2 ∑+- X 2∏, a hollow cathode discharge has been used operating in streaming air at low discharge current (∼). NO detection is achieved by a double-beam technique with single-beam optics. The experimental average absorption coefficient obtained for the γ (0,0) band is compared with the calculated value. Relevant NO spectroscopic information is reported.
Notizen: Various Donors in n-ZnSb and the Influence of Sample Treatment
Authors: Zeid A. Abou- , Schneider G.
Published: February 2015

Various donor doping of ZnSb is investigated. Te-doping yields the most stable n-type crystals at room temperature; the samples show p-type behaviour at low temperatures. The influence of surface effects is demonstrated. It was possible to prepare n-type ZnSb for the whole temperature range.
Cayley-Zahlen und Erhaltungsgesetze für Elementarteilchen / Cayley Number and Conservation Laws for Elementary Particles
Authors: Vollendorf F.
Published: February 2015

It is shown that the five conservation laws of charge, hyper-charge, barion number and the two lepton numbers lead to the construction of a commutative non-associative 24 dimensional linear algebra. Each element of the algebra is an ordered set of three Cayley numbers.
Resonance Broadening and Oscillator strength of the Mercury Absorption Line 1850 Å
Authors: Gebhard D. , Behmenburg W.
Published: February 2015

A new method for the determination of f-values of resonance transitions from wing-measurements of selfbroadened resonance absorption lines is described. The method is applied to the mercury resonance transition 61 S0→61P1, λ 1850 Å. The resulting f-value of 1.08±0.05 agrees well with those obtained from other methods.
Microwave Zeeman Spectrum of Hypochlorous Acid
Authors: Suzuki Masao , Guarnieri Antonio
Published: February 2015

The microwave-Zeeman-spectrum of HOC1 has been investigated with magnetic fields up to 25 kG. A method is described to perform the calculation of the Zeeman parameters independent from rotational constants and quadrupole coupling constants.
Der Einfluß magnetischer Felder auf die Torsionsscherung von MBBA / Torsional Shear Flow of MBBA in Magnetic Fields
Authors: Waltermann Th. , Fischer F.
Published: February 2015

Quantitative results are reported on the influence of a homogeneous magnetic field upon the torsional shear flow of a homeotropic layer at 22.5 °C. In subcritical fields Hx parallel to the layer, as well as in weak fields Hz normal to the layer, one gets K3/μ0 Xa = 3.76±0.2 A2 . In oblique magnetic fields (Hx , 0, Hz) one obtains (λ2-λ1)/μ0 Xa=(11.7±0.4)x1010 A2 m-2 s. In addition, a hysteresis effect in supercritical fields Hx and the formation of a long and straight magnetic wall are described. The magnetic wall becomes distorted under the action of the shear flow. Hereby a new domain can be produced which has a 180° inversion wall parallel to the boundaries of the layer.
Enrichment of 14CH4 by Thermal Diffusion for Use in Radiocarbon Dating
Authors: Kretner R. , Dickel G.
Published: February 2015

By means of a thermal diffusion column the range of the radiocarbon dating method can be extended by about 20 000 years. In order to calculate suitable dimensions and operation conditions, a theory of nonlinear enrichment is derived. On the basis of a formula which describes the dependence of the enrichment factor on time and the characteristic values of the column, a con-centric column of 11m length was constructed. The enrichment factors obtained for 13 CH4 as a function of time (up to 400 h) and pressure (150 -1500 Torr) and for 14CH4 at 740 Torr and up to 1000 h are presented and discussed. A method is described to indirectly determine the enrichment factor in the stationary state and the characteristic time.
Ein neues Verfahren zur Berechnung der Diffusionskoeffizienten in Multikomponentensystemen aus Meßdaten der quasistationären Diffusion / A new procedure for the determination of diffusion coefficients from quasi-stationary diffusion measurements in multicomponent systems
Authors: Meiske W. , Schmidt W. , Kahrig E.
Published: February 2015

Diffusion in an (n+1) -component system is described by Onsager's flow equations the integration of which leads in the case of quasi-stationarity to the differential equations d(Δc)/dt=-βD̅Δ c (Δc: vector of concentration differences between the compartments of the cell, D̅: matrix of integral diffusion coefficients, β: apparatus constant). Several procedures are known to determine these diffusion coefficients from such equations but all of them have certain disadvantages. In this paper a new method is described to compute the integral diffusion coefficients, which starts from the associated equivalent system of integral equations. The mathematical formalism is simple, and its numerical performance does not become more difficult with an increasing number of components of the system.
On the Calculation of the Force Constants for Halides AX4
n (Td). Using an Empirical Constraint F33 (F2)/F11 (A1) = Constant for Similar Molecules and Ions
Authors: Alix A. , Cerf C. , Rai S. N.
Published: February 2015

An empirical constraint for the determination of the force constants of a General Valence Force Field for the tetrahedral halides with the general formula AX4
n (where A = an element of the groupe II, III, IV, V and VI; X = F, Cl, Br and I and n = +1, 0, -1 and -2) is presented. The model is defined by a constant value of the parameter p= (ft -ftt) / (ft + 3ftt). The optimum value, p = 0.73, obtained for the mixed halides of chlorobromomethane is compared with those calculated from other force fields commonly used.
The Correlated Basis Function Method and its Application to Liquid 3He, Nuclear Matter and Neutron Matter
Authors: Nitsch J.
Published: February 2015

The method of correlated basis functions is studied and applied to the Fermi systems: liquid 3 He, nuclear matter and neutron matter. The reduced cluster integrals xijkl... and so the sub-normalization integrals Iijkl... are generalized to coinciding quantum numbers out of the set {i, j, k, I,...}. This generalization has an important consequence for the radial distribution function g (r) (and then for the liquid structure function) ; g(r) has no contributions of the order O (A-1). For 3 He the state-independent two-body correlation function g(r) is calculated from the Euler-Lagrange equation (in the limit of r → 0) for the unrenormalized two-body energy functional. For nuclear matter and neutron matter we adopt the three-parameter correlation function of Bäckman et al. Then the energy expectation values are calculated by including up to the three-body terms in the unrenormalized and renormalized version of the correlated basis functions method. The experimental ground-state energy and density of liquid s He can be well reproduced by the present method with the Lennard-Jones-(6 -12) potential. The same method is applied to the nuclear matter and neutron matter calculations with the OMY-potential. The results of the energy expectation values indicate a practical superiority of the unrenormalized cluster expansion method over the renormalized one.
Microwave Diagnostics of a Strong Arc Discharge Plasma in SF6
Authors: Musil J. , Žáček F.
Published: February 2015

The paper deals with the microwave free-space diagnostics of high collision arc discharge plasmas. It is found that information about the electron density N and the collision frequency ν in such a plasma can be obtained from the energy transmitted through the plasma by an electromagnetic wave. The phase of the electromagnetic wave cannot be used since it is almost the same as that of a wave passing through vacuum. These basic concepts are verified experimentally at a frequency of 37.5 GHz.

It is shown how the time dependence of the electron density in a plasma with constant and with time variable collision frequency may be evaluated.
Direkte Bestimmung der Geschwindigkeitskonstanten des Durchtritts vom kleinen zum großen Hohlraumsystem im Molekularsieb Typ 13 X für Sr-und Ba-Ionen / Direct Determination of the Rate Constants for the Sr- and Ba-exchange Between the Small and Large Channels in LMS 13 X
Authors: Frohnecke K. , Fischbach H.
Published: February 2015

Direct Determination of the Rate Constants for the Sr-and Ba-exchange Between the Small and Large Channels in LMS 13X The rate constants for the intracristalline Sr-and Ba-exchange between the small and large diameter channels of LMS 13X were measured. For this matter the method of interrupting the ion exchange was modified. It is assumed, that a first order reaction takes place. Using the rate constants and the diffusion coefficients, which were measured by Hoinkis and Levi, the total exchange of Sr 2+ and Ba 2+ could be calculated.
Die Sekundärelektronen-Ausbeute verschiedener Materialien bei Beschuß mit leichten Ionen hoher Energie / Secondary Electron Yield from Various Materials under the Impact of Light Ions at High Energies
Authors: Beck H. P. , Langkau R.
Published: February 2015

The backward emission of secondary electrons from thick targets of graphite, aluminum, copper, molybdenum and tantalum under the impact of protons, deuterons, 3 He-ions and a-particles has been measured for incident energies in the MeV-range. The data are discussed within the scope of theoretical considerations based on low-energy studies taking into account the contribution due to ;< 5-rays.
Das Rotationsspektrum des IBr / Rotational Spectrum of IBr
Authors: Tiemann E. , Möller Th.
Published: February 2015

The microwave spectrum of IBr was measured in the low rotational transition J = 3 ← 2 in order to resolve the hyperfine structure as completely as possible. Rotational constants and quadrupole coupling constants were derived for both nuclei. The observation of the rotational spectrum in different vibrational states yields the vibrational dependence of the rotational constants as well as of the hyperfine parameters. The Dunham potential coefficients a0, a1, a2, a3 are given.
UV Absorption Spectra of Methyl, Cyclopropyl Ketones
Authors: Al-Khafaji Jabria A. , Shanshal Muthana
Published: February 2015

The UV absorption spectra of some 1, alkyl, cyclopropyl, methyl ketones are recorded in different solvents. For the 1, methyl, cyclopropyl, methyl ketone (3) a Δ - π* band is observed in organic solvents. The spectra are discussed in terms of a second order perturbation of both Walsh and MO′s of cyclopropane and the carbonyl group. It is found that the hypsodiromic shift of the n-π* band in the cyclopropyl ketones is due to a destabilization of the π* MO. The appearance of a Δ - π* in (3) is due to a rotation of the carbonyl group from the bisected conformation and a stabilization of the π* MO.
On the Lattice Parameters of the Orthorhombic Low Temperature Phase of Crystalline Acetylene-d2
Authors: Koski Harri K.
Published: February 2015

Acetylene-d2, C2D2 , is known to exist in two crystal structures. The neutron powder diffraction data of the orthorhombic phase for temperatures between 4.2 K and 148.7 K have been analyzed and the refined lattice parameters and the calculated unit cell volume tabulated. By expressing the observations as functions of the vibrational energy, values for the Debye characteristic temperature and the static lattice and zero-point quantities are calculated with the method of least squares. Theoretical values for the coefficient of thermal expansion, quantities proportional to the isothermal compressibility, and the calculated density of solid C2D2 are given. The average frequencies associated with the characteristic temperatures for the lattice vibrations along the a-and b-axes are calculated. Finally, an estimate for the latent heat of the cubic-orthorhombic transition is obtained from the Clausius-Clapeyron equation.
Die Excimerenkinetik des 3,4-Benzo[a]pyrens / Excimer Formation Kinetics of 3,4 Benzo[a]pyrene
Authors: Hafner F. , Frey R. , Hauser M. , Heidt G.
Published: February 2015

The photophysical and kinetic constants are completely determined by photostationary and time-dependent fluorescence measurements. Deviations from the usual reaction scheme at higher concen-trations are caused by a quenching process of the excimer by the unexcited monomer. This diabatic process which is not observed with pyrene and naphthalene takes place in spite of the short excimer lifetime. A possible correlation between internal conversion and diabatic reactivity is discussed.
EMF Measurements on the Thermocell Ag(T1)/AgI/Ag(T2)
Authors: Shahi K. , Chandra S.
Published: February 2015

Thermal emf measurements have been carried out on AgI using reversible silver electrodes be-tween 75° and 300 °C. A sharp change in the magnitude of the thermoelectric power (Θ) has been observed at 146 °C corresponding to the β to a phase transition. The results may be represented by the equations

β-AgI: θ =- [(0.351 ±0.032) (103/T)+0.203 ± 0.083]mV/K, 70-146 °C,

a-AgI: θ =- [(0.052 ± 0.011) (103/T)+0.531 ± 0.031]mV/K, 146-300 °C.

From these the heats of transport of the Ag+ interstitials and ions respectively in the two phases have been calculated to be (0.351-h/2), h being the heat of formation of a Frenkel defect pair in β-AgI, and 0.052 eV, whereas the activation energies for conduction are 0.38 and 0.051 eV respectively. These results are compared with those of previous authors.
Notizen: Diffusion im flüssigen System Chlorbenzol + Brombenzol / Diffusion in the Liquid System Chlorobenzene + Bromobenzene
Authors: Haase R. , Kottmann R. , Dücker K.-H.
Published: February 2015

Results of measurements of the diffusion coefficient D for the ideal liquid system chlorobenzene+bromobenzene are presented. They cover the whole composition range at 295 K (≈ 22 °C). Within experimental accuracy, D is a linear function of the mole fractions. The product D η (η: viscosity) is a more complicated function of composition.
Notizen: Specific Volume Studies on Some Nematic Liquid Crystals
Authors: Bahadur Birendra
Published: February 2015

The temperature variation of the specific volume of two nematic liquid crystals (HBT and OBT) has been observed in both the nematic and isotropic regions. A sudden jump is observed in the vicinity of the nematic-isotropic transition indicating a first order phase transition. Pretransitional effects are found to occur only on the nematic side of the transition. This accords with the Maier-Saupe theory. Some parameters such as SK , A, the adiabatic compressibility, the Rao number, and the van der Waals constant are also determined.
Kinetic Theory of Thermal Diffusion in a Magnetic Field
Authors: Köhler W. E. , Halbritter J.
Published: February 2015

A kinetic theory of thermal diffusion in binary mixtures of polyatomic gases in an external homogeneous magnetic field is presented. It is based on the transport-relaxation equations obtained from the linearized Waldmann-Snider equation with the moment method. Under the assumption that the Kagan polarization is the decisive nonequilibrium alignment an expression for the thermal diffusion tensor in terms of Waldmann-Snider collision integrals is derived. In particular, mixtures of linear molecules with noble gas atoms are treated and the mole fraction dependence of the transverse effect is studied. As examples, the mixtures N2-Ar and N2-Ne are considered. Finally the order of magnitude of the transverse Senftleben-Beenakker effect of diffusion is estimated
Low Temperature Infrared Spectrometric Studies of Difluorodisulfane, Thiothionylfluoride and Difluorotrisulfane
Authors: Wanczek Karl-Peter , Bliefert Claus , Budenz Rudolf
Published: February 2015

The low temperature IR stretching vibrations of difluorodisulfane (FSSF) and thiothionylfluoride (SSF2), in the solid phase and in a cyclohexane matrix, of the mixtures FSSF -SSF2, FSSF-OSF2 and SSF, -OSF2, and of solid difluorotrisulfane (FS3F) have been investigated. While SSF, forms no distinct oligomers, a dimer with absorption bands at 635 and 682 cm-1 has been detected in the case of FSSF. These differences between FSSF and SSF, are rationalized by the different S-F bond lengths. A structure of the FSSF dimer similar to that of the sulfur tetrafluoride dimer is proposed. The low temperature spectrum of FS3F shows 3 bands in the frequency range between 460 and 1000 cm-1: 590, 605 and 680 cm-1, due to associated molecules. FS3F decomposes on warming. The main decomposition products containing fluorine are FSSF and SSF2. Mechanisms for the rearrangement and decomposition of the three compounds studied are discussed
Über den Zusammenhang zwischen Substituentenparametern und charakteristischen Gruppenfrequenzen / On the Relation between Parameters of Substituents and Characteristic Vibrational Frequencies
Authors: Morawietz Gerd , Bliefert Claus
Published: February 2015

The ability of simple relationships to approximate the characteristic group vibration frequencies using as parameters the mass, the Taft o* values, the Seth Paul X(R) constants, and the generalized Kagarise Xelf values has been examined for molecules of the general formula R-XY (XY = NO, OH, CN, SH, SF, SCl). It has not been possible to obtain linear relationships of sufficient generality and accuracy by applying the four parameters separately or by using parameter combinations
1/f Macroscopic Quantum Fluctuations of Elec- tric Currents Due to Bremsstrahlung with Infra- red Radiative Corrections
Authors: Handel Peter H.
Published: February 2015

Due to interaction with the quantized electromagnetic field, any current carrier involved in some scattering process may emit low frequency photons. This photon emission carries negligible energy but modulates the current nevertheless, resulting in 1/f and 1/Δf noise
Zur Theorie des stimulierten Raman-Effektes an Kristallen/ Theory of Stimulated Raman Effect in Cyrstals
Authors: Borstel G. , Merten L. , Rath K.
Published: February 2015

The theory of stimulated Raman effect in biaxial and uniaxial crystals is presented on the basis of a parametric process. For the system consisting of Stokes wave and polariton wave a dispersion relation is derived which allows to predict the threshold value of the stimulated process and the gain factor for real crystals.
Theory of the Polarized Fluorescence Experiment
Authors: Frehland Eckart
Published: February 2015

The static polarized fluorescence experiment is investigated for the most general case of arbitrary orientation distributions of transition moments in the fluorescent sample and arbitrary rearrangements of transition moments during the excited fluorescent state. It is shown that all available information is contained in a tensor of fourth order. The maximum number of independent components of this tensor is 36. Hence in the general case 36 polarized intensities must be measured in order to utilize the maximum available information. For special symmetries of orientation distributions this number is drastically reduced. In the case of vanishing rearrangement it is 15, for planar arrays (axial symmetry) not exceeding 11 and for spherical symmetry only 2. The results may be extended to the time-dependent polarized fluorescence experiment.