bluuebunny/crossref_metadata_2025 huggingface dataset:
Hochtemperatur-Festkörperchemie von Verbindungen der seltenen Erden mit Valenzinstabilität: Nichtstöchiometrisches TmSe und Mischkristalle / High Temperature Solid State Chemistry of Rare Earth Compounds with Valence Instability: Nonstoichiometric TmSe and Alloys
Authors: Kaldis Emanuel , Fritzler Benno , Peteler Winfried
Published: February 2015

The phase diagram of TmSe has been measured in the composition range 0.6 ≦ x ≦ 1.2 (x = mole Tm/mole Se) up to 2300 °C. Both phase diagram and lattice constants show the existence of a gross homogeneity range at 0.90 < x < 1.05. X-ray and electron diffraction at room temperature confirm the homogeneity of this phase and show no superstructures in this range but only a correlation of vacancies. A dramatic change of the lattice constant (1.7%) with nonstoichiometry shows that the latter controls the valence of Tm between 3 + and 2.71+. Density measurements indicate that both the solution of excess Tm or Se in the lattice leads to the formation of vacancies in the other sublattice. The experimental results can be explained by the existence of approx. 1% Schottky defects for all samples and nonstoichiometric vacancies increasing with deviations from stoichiometry up to 10% for the Se-rich phase boundary (each tenth lattice site vacant!). With increasing temperature the nonstoichiometric samples show two phase transitions: the first at approx. 1100°C for Tm-rich samples or approx. 1700°C for Se rich samples (the stoichiometric sample shows both transitions); the second for all samples at 2003°. At 2020 °C a eutectic appears at the composition of x = 1.00, its components melting at 2032 °C and 2028 °C. This shows that in the temperature range between the phase transitions and the eutectic temperature a decomposition of the homogeneity range must take place. This decomposition might be due to a valence segregation, the two components of the eutectic possibly being Tm2,71+Se and Tm3+Se. Various measurements indicate changes of the lattice stability in TmSe as a function of stoichiometry. Thus stoichiometric samples show a minimum melting point and solution-reaction calorimetry (with 4N HCl) indicates that the composition with the highest melting point (Tm3+Se) has the highest stability. As it is briefly discussed the unstable states may have important implications as active states for surface phenomena and catalysis. Further change of the Tm-valence in a TmSe-containing compound exceeding the range Tm3+↔Tm2,71+ may be achieved by mixed-crystal formation. The lattice pressure in TmSe is changed by chemical substitution leading among others to the interesting mixed crystal systems TmSe1-xTex and Tm1-xEuxSe. The first shows two pressure-induced phase transitions accompanied by a change of the Tm-valence from 2.25+ → 2.52+ and 2.52+ → 2.93+. Density measurements show that when the lattice collapses the number of vacancies nears 10%.
Solutions of Partial Differential Equations for Mean Molar Functions
Authors: Wittig F. E.
Published: February 2015

The well known formulas for computing the partial molar functions from a given mean molar function are treated as deferential equations for computing the mean molar function from any given partial molar function. Solutions do not depend on the number of components, but only on the choice of three indices: the index d of the dependent mole fraction xa to be eliminated prior to any computations, the index j of a pivot mole fraction xj and the index i of the partial molar function yi. An arbitrary number of additional mole fractions of the other components safe xd may be linked to the pivot mole fraction xj. The simple solution: y = (xj - δij) Iij, yi = (xj - δij)2 Xij and Xij = d Iij/dxj holds for an arbitrary number of components, if the (c - 2) mole fractions xj safe xd and xj are transformed to new variables found from the auxiliary equations. Three different cases arise if either i = d, i = j or i ≠ d, i ≠ j is chosen. Formulas for the three sets are provided. As an example a simple interpolation formula for ternary systems is discussed.
Boltzmann Equation Approach to Fröhlich’s Vibrational Model of Bose Condensation-Like Excitations of Coherent Modes in Biological Systems
Authors: Kaiser Fr.
Published: February 2015

A modified Peierls-Boltzmann transport equation formalism for phonons is applied to Fröhlich’s vibrational model. In this model a set of oscillators it nonlinearly coupled to the rest of the system, which can be taken as a heatbath. An external energy supply leads to an additional excitation of the modes. The Hamiltonian for the model is presented and the kinetic equations are derived. The steady state solutions show that under certain conditions the lowest mode be-comes strongly excited, when the phonon flux increases. The resulting excitation far above the thermal value corresponds to a preferred channeling of energy into a single mode (Bose condensation-like excitation). Correspondence with Fröhlich’s rate equation approach is established and the quasi phase transition-like behaviour is discussed
Ortho and Parahydrogen in Interstellar Material
Authors: Reeves Robert R. , Harteck Paul
Published: February 2015

Since H2 is the most abundant molecule in the universe, the ratio of orthohydrogen molecules to parahydrogen in interstellar space is of interest. H2, formed by any exothermic reaction will be in the ratio of 3: 1 according to their statistical weight. This corresponds to the high temperature equilibrium. At the low prevailing temperatures of interstellar space, the thermo-dynamic equilibrium should be shifted to the parahydrogen side. In the gas phase this shift can occur only over chemical reactions which are close to thermally neutral. In addition, it can be concluded that two ion scrambling reactions dominate the process and these both involve positive hydrogen ions. In special cases, surface catalysis on interstellar dust particles may add to the equilibrating process. The highly forbidden process of transition by radiation J = 1(ortho) → J = O(para) + hv can only play a minor role in this catalysis
Structure and Properties of Vacuum-Deposited Cadmium Thin Films
Authors: Halder N. C.
Published: February 2015

Thin films of Cd were prepared by vacuum deposition onto glass plates at temperature of 45 °C and pressure of about 10-6 torr. Several good quality films of various thicknesses (15,000 ~ 28,000 Å) were made. The films were characterized by strong preferred orientation along the 002 planes parallel to the surface of the substrate, which were found to be thickness dependent. In particular, the 002, 100 and 004 peaks were many times stronger than their corresponding diffraction peaks obtained from powder specimens. Both the real and imaginary parts of the Fourier coefficients were considered for line broadening analysis. The particle size (which is also called the average size of the coherently diffracting domains in a direction perpendicular to the diffracting planes), microstrain (which is usually called the mean strain in a given direction) and faulting were determined. A systematic study for all the diffraction peaks indicates an increase of average particle size D̅ from 546 to 620 Å in the above thickness range with no apparent anisotropy for the 100, 002 and 004 directions. The microstrain, however, decreased as much as 50% in this thickness range and showed a considerable amount of anisotropy. The fault parameters α (deformation fault probability) and β (growth fault probability) decreased rather rapidly for all directions
Lattice Dynamics and Thermal Expansion of Thulium
Authors: Rao R. Ramji , Rajput A.
Published: February 2015

The lattice dynamics, lattice specific heat and thermal expansion of the rare-earth metal thulium are worked out applying a model based on Keating’s method. A frequency distribution function involving 50,880 frequencies has been employed. Using the calculated lattice heat capacity, the experimental Cp data of thulium are analysed to get the magnetic contribution to the specific heat in this metal. The energy of magnetic ordering and the magnetic entropy increase involved in the transition from the ordered antiferromagnetic phase to the disordered paramagnetic phase are evaluated. The lattice parameters and volume of thulium are also calculated as a function of hydrostatic pressure and compared with the experimental results
Investigation of the H1 Spin-Lattice Relaxation Times of Some Ammonium Compounds
Authors: Köksal F.
Published: February 2015

The temperature dependence of the proton spin-lattice relaxation times of (NH4)2Al(SO4)2, (NH4)2 MoO4, NH4NH2SO3 and (NH4)2SnCl6 has been investigated in the temperature range 100- 500 K. The experimental results indicate that intra H-H dipolar interaction, modulated by reorientational motion of the ammonium ion, is the dominant relaxation mechanism between 100 and 200 K. The activation energies for the reorientational motion of the ammonium ions were found to be 1.54, 1.56, 0.99, and 0.91 kcal/mole, respectively. Furthermore, it has been detected that above 200 K the spin-rotational interactions of the ammonium ions contribute to the spin-lattice relaxation. The average value of the mean-square spin-rotational interaction constant for NH4
+ was found to be C2 = 1.42 × 1010 s-2
Evidence of a New Decay Mode of 9
ΛB
Authors: Mandal P. , Bhattacharya D. K. , Saha M. , Sen P. K.
Published: February 2015

In a sample of about 200 hyperfragments produced in the interactions of 1.8 GeV/C K--mesons in nuclear emulsions, one example of the hitherto unobserved decay 9
ΛB →π- + 1H + 1H + 7Be has been established. The value of the Λ-hyperon binding energy (BΛ) obtained is 7.37 ± 0.42 MeV
Electric Dipole Moments of Some Heterocyclic Cyclobutane Derivatives in Benzene Solution
Authors: Sanesi M.
Published: February 2015

The electric dipole moments of some heterocyclic cyclo-butane derivatives have been measured in benzene solution at 20 °C. The observed values are compared with those calculated by vector addition for different steric configurations
Boundary Conditions for the Distribution Function and for the Moments of a Gas at a Moving Wall
Authors: Vestner H. , Waldmann L.
Published: February 2015

As a slight generalization of previous work [1], boundary conditions for the distribution function of a monatomic gas at a moving solid or liquid wall are derived from the interfacial entropy production. The new scheme is compared with the conventional one. Boundary conditions for a set of moments of the distribution function are obtained by taking the corresponding moments of the new kinetic boundary condition. With a special set, the details are worked out. Finally, a simple two-parameter model for the interfacial kernel is designed and discussed.
Blackbody Radiation in the Rectangular Wave Guide
Authors: Eckhardt W.
Published: February 2015

Electromagnetic (EM-)fluctuations in the rectangular wave guide are considered. In the limit of the empty (lossless) wave guide the partial mode densities, the volume averaged correlations and the internal energy are discussed in both, the high and the low temperature representation. The results are compared with the corresponding quantities in the cube, the slab resonator and the infinite isotropic space.
Proton Magnetic Resonance Study of Molecular Motion in Solid Silver Sulfate Tetrammine, Ag2SO4 · 4NH3
Authors: Kummer Norbert , Ragle John L. , Weiden Norbert , Weiss Alarich
Published: February 2015

The spin lattice relaxation time T1 and the second moment of the proton magnetic resonance were studied on polycrystalline samples of Ag2SO4 · 4NH3. The wideline NMR measurements show a rapid reorientation of the NH3 groups around their threefold axes in the temperature range 250 K ≦ T ≦ 380 K. Below T ≈ 250 K, the rotation of the NH3 starts freezing-in. From Ti measurements an activation energy of 27.5 kJ mol -1 for the rotation was found for temperatures above 210 K. Around 330 K a phase transition has been observed by T1 measurements which is not recognized by wideline NMR measurements in the range 77 K ≦ T ≦ 375 K. The results are discussed and compared with other NMR studies on solids containing NH3 groups.
Determination of the Plasmaparameters and the Suprathermal Microfields in a Critical Velocity Rotating Plasma
Authors: Möbius E.
Published: February 2015

In a critical velocity rotating plasma the profiles of the Hel 4471 Å and Hel 4922 Å lines have been investigated with high time resolution using an optical multichannel system in order to determine suprathermal electric microfields. The plasma density has been measured simultaneously with a CO2 laserinterferometer. The existence of low- and highfrequency fields is proved by the occurrence of a strongly enhanced forbidden line component and plasma satellites in the front of the current spokes, which are typical for this plasma. Thus the occurrence of electrostatic instabilities and a turbulent heating process at the critical velocity is confirmed experimentally
Temporal Development and Properties of an Overdense Plasma Produced by High Power Microwaves in a Coaxial Discharge Device
Authors: Kampmann B.
Published: February 2015

A coaxial plasma-waveguide-system exhibits strong absorption near its dipole resonance. Due to the plasmaguide-mode overdense plasmas can be generated in this device. Ionization dynamics and properties of this discharge are investigated by means of different diagnostic methods; the results are compared with analytical calculations of the dispersion relation in the plasma-waveguide-system. In this way the occurrence of nonlinear absorption mechanisms in presence of strong microwave fields is examined
The Role of Hydrogen Molecular Lines in the Vicinity of Hβ
Authors: Piel A. , Richter H.
Published: February 2015

The profile of Hβ emitted by a low pressure afterglow discharge (p0 = 500 Pa, ne = 1· 1015 cm-3) is measured with 1/μs temporal resolution on a 500-channel optical multichannel analyzer (1 channel = 0.09 Å). Several structures appearing superimposed on thermal line profile can be identified as hydrogen molecular lines. These results affect earlier observations under very similar conditions which have been interpreted in terms of plasma satellites
Isoelectronic Changes in the Behaviour of Nonrelativistic Electron Density Near the Nucleus in Free Ions
Authors: Sen K. D.
Published: February 2015

It is shown numerically that the nonrelativistic Hartree- Fock-Slater total electronic density near the nucleus in 3d5, 4d5 and 5d5 ions can be approximately represented as ANZ3 exp(- 2Zr) where AN is a constant depending on the number of electrons
Ferromagnetic State of a Model Chain System
Authors: Kertész M. , Koller J. , Ažman A.
Published: February 2015

Ferromagnetic states of two linear chains are determined. The comparison with the solution of the restricted Hartree-Fock method shows that such states are energetically very unlikely
Influence of Relaxing Defects on the Paraelectric-Ferroelectric Phase Transitions of Rochelle Salt
Authors: Petersson J.
Published: February 2015

It is well known that different types of crystal defects influence the static and dynamic behaviour of the dielectric polarization of Rochelle salt crystals. Particularly strong effects appear near the paraelectric-ferroelectric phase transitions. In this paper it is shown that a slightly modified relaxing defect cell model which has been developed [1] in order to explain the narrow central peaks observed near structural phase transitions adequately describes the interaction between the strongly temperature dependent relaxational motion of the order parameter and the relaxational motions of the various defect modes. This theory is shown to be equivalent to a phenomenological Landau Khalatnikov approach, which so far has only been used to characterize the macroscopic dielectric behaviour of Rochelle salt crystals with defects near the phase transitions, and which in a previous work [16], has been developed in order to give a general description of central peak phenomena caused by defects. For instance the so called very fast after effect and its influence on the phase transitions is discussed in more detail.
Further Study on the Forms of Umbelliferone in Excited State. Part II
Authors: Taszner Stanislawa , Grzywacz Jerzy
Published: February 2015

The assumption [1] that there exist two excited tautomeric forms of umbelliferone in ethanolaqueous solutions is compared with experimental results. Agreement is achived by assuming that the equilibrium between the two forms is dependent on the polarity of the solvent.
Die Schwingungsstruktur der Shpolskii-Spektren von Anthracen, 9-Methyl-und 9.10-Dimethylanthracen in n-Hexan bei 77 K II.Absorption / The Vibronic Structure of Shpolskii Spectra of Anthracene, 9-Methyl- and 9,10-Dimethyl - anthracene in n-Hexane at 77 K II.Absorption
Authors: Jung Ch. , Kawski A. , Zukowska M. I.
Published: February 2015

The absorption spectra of 9-methyl- and 9,10-dimethylanthracene in n-hexane and of anthracene in n-heptane at 77 K were measured spectrographically. From the comparison with calculated frequencies and intensities it can be shown that the observed intense vibronic lines correspond to the same totally symmetric vibrations as in the earlier measured fluorescence spectra. Compared with the fluorescence spectra deviations from the mirror symmetry were observed. In the case of anthracene and 9,10-dimenthylanthracene they result first of all from different intensities of the corresponding vibronic lines, and it can be shown that these differences are mainly due to the Duschinsky-Effect. For 9-methylanthracene the great frequency difference of one totally symmetric vibrations perturbs the mirror symmetry also.
Solid State Transitions in Alkali Alkanoates: Diffractometric and Conductometric Measurements on Lithium, Sodium and Potassium Propanoates
Authors: Cingolani A. , Spinolo G. , Sanesi M.
Published: February 2015

Conductometric measurements on solid lithium, sodium and potassium propanoates and X-ray powder diffraction measurements on the sodium and potassium salts have been performed over temperature ranges including solid state transitions. The temperature dependence of the transport and lattice parameters of the different crystalline phases and the changes of the same parameters in correspondence with phase transitions have been put into evidence.
Time-resolved Microwave Double Resonance in Four Level Systems: H2CO
Authors: Glorieux Pierre
Published: February 2015

Experiments have been performed using time-resolved spectroscopy techniques in a four-level double resonance scheme. The time-resolved variations of radiation probing the populations of a K-type doublet of H2CO have been studied as pump radiation suddenly switched on and off induces population changes between levels of another K-doublet. Non-exponential behavior with characteristic times longer than the relaxation time associated with pressure broadening has been exhibited. A theoretical treatment of this effect, using a generalized density matrix equation, is proposed. It gives reasonable agreement with the observed time dependences.
Mössbauer Studies on some Europium(III) β-Diketonate Complexes
Authors: Medhi O. K. , Agarwala U.
Published: February 2015

Some Europium(III) dibenzoylmethide and benzoylacetonate complexes have been subjected to Mössbauer studies at liquid nitrogen temperature. An attempt is made to discuss covalency in these complexes in terms of 6s, 4f and/or 5d orbital participation in the bond formation. Small linewidths are correlated to less symmetric structures. Resonance effects reflect the polymeric nature of these chelates.
Silicon Über die strahlende Rekombinationswahrscheinlichkeit B von eigenleitendem Silizium / On the Radiative Recombination Probability B in Intrinsic
Authors: Wasserrab Th.
Published: February 2015

In 1974 a theory of the radiative recombination including the Coulomb interaction and the exciton recombination was published by Schlangenotto et al. Now, a quantitative evaluation of this theory was carried out for Si: it shows a strong enhancement of the recombination probability, compared with the theory of van Roosbroeck and Shockley, and yields a remarkable agreement with the measurements.
An Application of Karman’s Energy Transfer Process in Hydromagnetic Turbulence
Authors: Pramanik G. C.
Published: February 2015

A modified version of Chandrasekhar’s equation is derived with the aid of Karman’s energy transfer process for the decay of hydromagnetic turbulence in the limiting case of zero viscosity and infinite electrical conductivity. It is found that the asymptotic behaviour of self-preserving solutions of the aforesaid equations leads to F(k, t)≈k4 , (c = 2/7), G(k, t)≈k6 , (c = 2/9) as k→0 and F(k,t)≈k-5/3 ,G(k,t)≈k-5/3 for k→∞.
Energy Transfer in Competition to Charge Transfer as a Method to Determine the Rate Constant for Charge Carrier Injection in the Sandwich System: Cyanine Dye Monolayer/p-Chloranil Crystal
Authors: Killesreiter Hermann
Published: February 2015

A new method is described to calculate the rate constant for charge transfer (CT) from an excited dye to a molecular crystal by taking into account competing energy transfer to a metal electrode. For the system oxacarbocyanine dye/p-chloranil single crystal in a sandwich arrangement with additional arachidic acid monolayers and evaporated aluminium electrodes, based on photocurrent and fluorescence measurements kCT - (1.5 ± 0.7) 109 sec-1 has been calculated.

This overall rate constant is discussed in terms of a detailed but simple reaction scheme for charge carrier injection. It turned out to be equal to the dissociation rate constant of the excited dye times the quantum efficiency ΦCT for dissociation of an intermediate “charge transfer” state. Dissociation occurs from a vibrationally relaxed excited state of the dye.

Finally, comparison is made with a straightforward calculation using the well-known unipolar current density. Nearly quantitative agreement of estimations emphasizes the use of the mono-layer technique to build "dry" electrochemical cells in order to study the principles of photo-electrochemical reactions.
Gas Electron Diffraction Study of the Molecular Structure of Di-2-pyridyl Sulphide
Authors: Rozsondai B. , Hargittai I. , Pappalardo G. C.
Published: February 2015

The gas-phase electron diffraction study of di-2-pyridyl sulphide has yielded rg(S-C) 1.786 ± 0.004 Å and ∢ C-S-C 104.4 ± 1.7°. The dimensions of the pyridyl groups were found to be consistent with those of free pyridine molecules. Models with various conformational properties could be used to approximate the experimental data.
Group Electronegativities: as Empirically Estimated from Geometrical and Vibrational Data on Sulphones
Authors: Hargittai Istvàn
Published: February 2015

The S=O bond lengths and the S=O bond stretching frequencies characteristically change with changing ligand electronegativities in the XSO2Y sulphone series. Empirical relationships have been established between the S=0 bond length and the sum of the ligand electronegativities (χX+ χY) and also between the mean stretching frequency and (χX + χY)-These relationships may be used for estimating group electronegativities from geometrical and vibrational data or to predict bond lengths, bond angles and stretching frequencies from ligand electro-negativities.
Einfluß der nematischen Ordnung auf die Fluoreszenz von Perylen und 4-Dimethyl-amino-4′-nitrostilben / Influence of the nematic order on the fluorescence of perylene and 4-dimethyl-amino-4’-nitrostilbene
Authors: Ullrich Gunter
Published: February 2015

The temperature dependence of absorption, emission and fluorescence-decay in EBBA has been investigated. The total absorption power μ=μ∥+2·μ⊥ was found to be constant over the whole investigated temperature range. For perylene a decrease of the quantum-efficiency with growing temperature was observed, but not for 4-dimethyl-amino-4′-nitrostilbene (DMANS). In the binary system an energy transfer via dipol-dipol interaction was observed. In the ordered phase energy-transfer distances about 30 Å and less were computed.
Torsional Shear Flow of Nematic and Cholesteric Liquid Crystals. Part I: Nematic Phase
Authors: Wahl J.
Published: February 2015

The simple shear flow of a homeotropic nematic layer in an electric field normal to the layer is studied theoretically and experimentally. Several material constants of MBBA are determined as a function of temperature.
Electrical Resistivity and Phase Separation in Dilute Liquid Alloys of Sodium in Selenium
Authors: Marel C. van der , Lugt W. van der
Published: February 2015

The electrical resistivities of liquid selenium and seleniumrich Na-Se alloys have been measured. The results of dilute alloys are interpreted in terms of percolation theory. A previously determined phasediagram was found to be incomplete.
The Measurement of Rotational Relaxation Time T2 for CH3C15N Self-and Foreign Gas Collisions
Authors: Mäder H. , Bomsdorf H. , Andresen U.
Published: February 2015

We report on the measurement of T2 for several rotational transitions of CH3C15N. The transient emission signal is investigated at different temperatures for the pure gas and mixtures with He and H2, and effective collision diameters are derived from the pressure dependence of T2.
Condensed Aromatics. Part III. In-Plane Molecular Vibrations of Pyrene
Authors: Cyvin S. J. , Cyvin B. N. , Brunvoll J. , Whitmer J. C. , Klaeboe P. , Gustavsen J. E.
Published: February 2015

A new force field is developed for the in-plane vibrations of condensed aromatics using pyrene as a test molecule. Only five parameters are employed in this force field, which improves a four- parameter approximation previously investigated. Still the simple five-parameter approximation gives calculated vibrational frequencies in good agreement with those from the more elaborate Califano-Neto force field.

In the course of the normal coordinate analysis the Hüekel molecular orbitals have been de­duced. The CC stretching parameters were modified by means of the calculated bond orders. A complete set of independent symmetry coordinates (both in-plane and out-of-plane) for the pyrene molecular model was developed.

New experimental data from infrared and Raman spectra for pyrene are reported.

Also the mean amplitudes of vibration are studied in detail. It is concluded that the simple five-parameter approximation gives reliable mean amplitudes, which undoubtedly are accurate enough for the interpretation of gas electron diffraction data.

Finally the calculated frequencies and mean amplitudes of benzene are given. The mean amplitudes are again found to be very accurate in spite of some substantial inaccuracies in the frequencies.
Notizen: On the Invariance of Distribution Functions
Authors: Oxenius J.
Published: February 2015

The Lorentz invariance of the fine-grained one-particle distribution function of a gas, as well as that of multiple­time many-particle distribution functions, is shown to be a consequence of the very definition of a physical event, so that it requires no formal proof. Since it is independent of any special property of Lorentz transformations, this invariance holds quite generally for arbitrary transforma­tions of space-time coordinates.
A Simple and Convenient EPR Standard for Determination of g-Factors and Spin Concentrations
Authors: Schmitz B. , Jakubith M. , Lehmann G.
Published: February 2015

The commercially available cement Picein 80 has been tested and successfully used for the determination of g- factors and spin concentrations at X- and Q-band frequencies. The main advantages compared to other standards are a very small space requirement and the fact that the concentra­tion of the standard can be easily adjusted to the signal intensities of the sample. This standard exhibits a single line at a g-factor of 2.0041 with a halfwidth of .47 mT and a spin concentration of 2.1015 spins/mg Picein. An additional weaker resonance occurs at g = 2.0177, and at Q-band a partly overlapping multiplet with 5.8 mT separation is observable, but the intensities of both signals are low com­pared to that of the main signal. This standard is applicable over the whole range of useful spin concentrations, and the linewidth makes it particularly useful for measurements on transition metal ions in diluted single crystals.
Deuterium Relaxation in Specifically Labeled Lecithin-Bilayers
Authors: Peters Andrew , Kimmich Rainer
Published: February 2015

Deuterium magnetic relaxation measurements are reported for two samples of specifically labeled dipalmitoyl lecithin bilayers in the temperature range 0° to 60 °C. While the liquid-crystalline phase shows a "dynamic gradient" along the alkane chains, which is already known from 13C-investigations, there is no such gradient in the gel phase at least between the second and tenth methylene group. Moreover there is a common T1-minimum compatible with that observed in studies of the (non-specific) proton relaxation.

Deuterium signals from the gel phase could only be detected by a combined spin-locking / echo method allowing to substract spurious signals arising from magneto-acoustic ringing typical for low-frequency / high-field pulse experiments in iron magnets.
Synthesis and Properties of a New Kind of One-Dimensional Conductors. 1. General Aspects
Authors: Hanack Michael , Seelig Friedrich Franz , Strähle Joachim
Published: February 2015

A model for a new kind of one-dimensional conductors is presented. The compounds consist of square-planar metal complexes MX4 which are polymerised via bridging ligands L to linear chains. The bidentate ligand L, e.g. C2
2-, leads to the formation of a linear π-system along the chain, which is essential for the conductivity. The square-planar complex can be, for example, a metal phthalocyanine. MO-calculations show that this kind of polymer gives rise to a suitable energy band structure. An advantage of the new one-dimensional conductors is their flexibility; different combinations of the square-planar ligand system, the bridging ligand, and the central metal atom can be used. First experimental studies show that the preparation of the proposed conductors is possible.
Molecular Dynamics Study of Aqueous Solutions IX. Dynamical Properties of an NH4Cl Solution
Authors: Szász Gy. I. , Riede W. O. , Heinzinger K.
Published: February 2015

The dynamical properties of an aqueous ammonium chloride solution have been calculated from a molecular dynamics simulation over 3.5 picoseconds at a temperature of 301 K where the basic periodic cube contained 200 water molecules, 8 ammonium ions and 8 chloride ions. The effective pair potentials are based on the ST 2 water model, a rigid tetrahedral four point charge model for NH4+, and a single point charge model for CI-. The coefficients of self-diffusion and of rotational diffusion, the spectral densities of hindered translations and of librations, the correlation times of the dipole moment vector and the vector connecting the two protons in a water molecule are reported separately for the various subsystems - NH4+ , Cl-, bulk water, hydration water of NH4
+ and CI- - and are compared with the available experimental data. Implications with respect to the structure breaking ability of the ions are discussed.
Luminescence Spectra of Trans-Bis(N-Alkyliminodiacetato)- Chromate(III) Complexes
Authors: Wernicke Rainer , Schmidtke Hans-Herbert , Hoggard Patrick E.
Published: February 2015

Luminescence spectra at 85 K have been recorded for a series of chromium (III) complexes with alkyliminodiacetates (RIDA) of the form K[Cr(RIDA)2], R=M(methyl), E(ethyl), n-P(n-propyl), i-P(isopropyl), n-B-(n-butyl), and t-B (t-butyl). Infrared and far infrared spectra of room temperature samples were also recorded.

All of the RIDA complexes exhibited the vibronic spectrum, with a remarkable shift of the intensity maximum away from the zero phonon line, which is characteristic of trans geometry in these complexes pointing to a 2E (tetragonal symmetry label) luminescent state. A comparison of vibronic intervals with IR data suggests several bands which may be indicative of iminodiacetate coordination.
The Role of Dislocations in the Thermal Dehydration of Lithium Formate Monohydrate
Authors: Flor Giorgio , Berbenni Yittorio , Marini Amedeo
Published: February 2015

The kinetics of Lithium Formate Monohydrate (LFM) dehydration (single crystal samples) has been investigated at constant temperature (317 < T < 353) under dynamic vacuum both optically and thermogravimetrically.

The process takes place with an induction period followed by a constant rate period. The first one is characterized by a surface nucleation which occurs mostly in connection with dislocations emerging on the (021), (110) and (010) faces and at the vertex-intersections of these planes; the second one corresponds to the advancement of a reaction interface (formed on the planes with l ≠ 0) along the c-axis.

This topochemical model has been interpreted on the basis of the different features of the actual dislocations and of the reticular geometry of the LFM crystal.
Investigation of T1-Relaxation for OCS Rotational Transitions by Self-and Nonpolar Foreign Gas Collision
Authors: Mäder H.
Published: February 2015

The pressure dependence of 1/T1 has been measured at temperatures ≅ 300 K and ≅ 200 K for the carbonyl sulfide J,|M| = (0, 0)-(1, 0), (1, 0)-(2, 0), (1, 1)-(2, 1), (2, 0)-(3, 0), (2, 1)-(3, 1) and (2, 2)-(3, 2) rotational transitions by using a π, τ, π/2 pulse sequence method. T1 relaxation has been investigated for the pure gas and mixtures with He, Ne, Ar, Kr, H2, O2, N2 and CO2. The effects of molecular motion are discussed theoretically by considering the microwave field inhomogeneity and collisions of molecules with the walls of the sample cell.
Absorption magnetoakustischer Wellen in einem Hoch-Beta-Plasma
Authors: Moser F. , Räuchle E. , Schneider E. , Schüller P. G.
Published: February 2015

Absorption of magnetoacoustic waves in a high beta plasma The radial propagation and absorption of magnetoacoustic waves (m = 0, kz = 0) in a radially inhomogeneous, high beta plasma column of a theta pinch is investigated both theoretically and experimentally. It is shown, that viscosity is the dominant dissipative mechanism. Power absorption up to 10 MW is obtained, which corresponds to an average heating rate of 5 eV/μsec per particle.
Solubilities of Silver and Copper in Their Molten Halide Mixtures AgClx Br1-x and CuClx Br1-x
Authors: Schuster E. , Schwind A. F. , Vötsch R. , Weil K. G.
Published: February 2015

Solubilities of silver and copper in their molten salt mixtures AgClxBr1-x; and CuClxBr1-x were measured as a function of T and x. From the temperature dependence of the solubilities, the enthalpies and entropies of dissolution could be obtained as a function of x. Unexpectedly these functions vary nonmonotonously with x. The enthalpies and entropies of solution were calculated from the experimental values, using literature data for the sublimation functions. They are found to be linearly correlated. The results are tentatively discussed under consideration of the covalent nature of the melt.
NMR-Untersuchungen über molekulare Bewegungsprozesse in Phenylensulfiden
Authors: Jurga J. , Eckert H. , Müller-Warmuth W.
Published: February 2015

Internal motion in poly (p-phenylene sulfides) and in some low-molecular phenylene sulfides has been studied using NMR relaxation and broad line techniques. The relaxation rates T1
-1 in the laboratory frame at 30 or 15 MHz, and T1e
-1 in the rotating frame at 45 kHz, and the second moments (or local fields or linewidths) have been measured over an extended range of temperatures for five different materials. For the polymers, the most important process has an activation energy of approximately 40 kJ/mole; it is ascribed to reorientational random oscillations of the phenylene groups, and it depends upon the detailed polymer structure. The origin of further processes of motion observed with activation energies of 20 and 11 kcal/mole is discussed. The rather narrow lines which occur in the NMR spectra at temperatures well above the glass transition are explained by the mobile fraction of chains of the non-crystalline regions.
Surface Tension of Water. The Fowler Model
Authors: Borštnik B. , Janežič D. , Ažman A.
Published: February 2015

The surface tension and surface energy of water is calculated using the Fowler approximation. The direct Monte Carlo integration and the calculation using the atom-atom pair correlation funtions are reported. The configuration interaction pair potential was used. The results show that feasible agreement with the experiment can be obtained.
Isoelectronic Changes in the Core Radius of Fe3+ and Ru3+ Like Ions
Authors: Rao C. V. R. , Sen K. D.
Published: February 2015

Isoelectronic changes in the core radius rm , defined as the last minimum in the total radial charge density distribution function 4 π r2 ϱ(r), have been computed for Fe 3+ and Ru 3+ like ions using Hartree-Fock-Slater wave functions. It is found that a linear relationship rm
-1 = A' Z + B' holds good within each series. An attempt is made to justify this empirical relationship.
Electric-field Dependence of Nuclear Magnetic Shielding and Susceptibility of Hydrogen and Hydrogen Fluoride Molecules
Authors: Žaucer M. , Ažman A.
Published: February 2015

The components of t h e tensors σ(1), σ(2) and χ(1), χ(2) which describe the linear and quadratic electric-field dependences of the nuclear magnetic shielding and susceptibility are computed for H2 and HF molecules using a gauge invariant double finite perturbation SCF approach. This approach is suitable for the discussion of intramolecular and intermolecular environmental effects and the effect of electric-field gradient is pointed out
Über die Struktur von Si-, Ge-, Sn- und Pb-Schmelzen / Structure of Si-, Ge-, Sn-, and Pb-melts
Authors: Gabathuler J. P. , Steeb S.
Published: February 2015

The structure factors of the molten elements Si and Ge were determined by means of neutron diffraction. Together with the structure factors of molten Sn and Pb, taken from literature, specific variations in the run of the curves can be detected. Especially, a shoulder on the larger g-side of the main maximum becomes larger going from Pb to Si. A model is given which describes these melts as being composed of hard spheres and tetrahedra. The concentration of tetrahedra is evaluated
Electroelastic Effect in Tourmaline
Authors: Kittinger E. , Seil K. , Tichý J.
Published: February 2015

Measuring the electric field induced frequency shift of tourmaline resonators the electroelastic constants g311 and δ333 are determined. These constants may be interpreted as describing either the electric field dependence of an elastic constant or the stress (strain) dependence of a piezoelectric constant, Fields u p to about 3 x 106 V/m were used. Within this range the effect is linear and is of the same order as in α-quartz
Oll the Odd-Even Effect in the Helix of Non-Sterol Cholesterogens
Authors: Meer B. W. van der , Vertogen G.
Published: February 2015

A model is proposed to explain the alternation of the screw-sense of the helix with the number of bonds between the chiral centre and the ring system in chiral compounds with nematic-like molecular structure
Experimentelle Realisierung der Beziehung I~sin2 x/x2 auf röntgenographischem Wege / Experimental Verification of I ~ sin2 x/x2 by X-Ray Diffraction Measurements
Authors: Fischer W. , Wissmann P.
Published: February 2015

It is shown that the equation I ~ sin2 x/x2 well-known from light optics can be proved experimentally even by x-ray diffraction measurements on thin films. All side maxima appear with the right order of magnitude if an optimal film thickness of about 90 Å is chosen
Hydrogen Stark Broadening by Ion Impacts on Moving Emitters
Authors: Seidel Joachim
Published: February 2015

The “classical path theory” for the plasma broadening of hydrogen lines calls for a closer examination of the influence of radiator motion on Stark profiles. For a radiator with constant velocity Stark broadening is effected by an anisotropic plasma, and in a frame of reference moving with the emitter the line shape depends not only on the radiator speed but on the direction of emission as well. From this, a somewhat intricate correlation of Stark and Doppler broadening arises which has to be taken into account in the calculation of the full line profile. As an example, broadening by plasma ions is investigated in the impact limit where a distinct dependence of Stark broadening on the emitter velocity is found especially for very heavy, immovable ions.
Time Periodic Perturbations of Quantum Systems
Authors: Kelemen A.
Published: February 2015

We discuss a method of calculating the mean energy of a quantum system if the latter is subjected to time periodic perturbations. This, e.g., includes the possibility of determining shapes of spectral lines for an arbitrary distribution of nonperturbed energy levels. The method is studied on a system of order 2 whose spectral line is exactly lorentzian. We prove that the next to lowest approximation reproduces this form exactly.
Rate Coefficients and Product Ion Distributions for Reactions of CO2 · CO2
+ Ions with Neutral Molecules at 300 K
Authors: Rakshit A. B. , Warneck P.
Published: February 2015

Reactions of CO2 · CO2
+ ions with CO, N2O, CH4, H2O, O2, COS, C2H2, C2H4, C3H6, NH3, CH3NH2, and NO have been studied using a drift tube mass spectrometer with selected ion injection. In most cases, the major reaction channel is charge transfer. Molecular displacement (switching) occurs also in several cases. In general, the measured rate coefficients agree with those calculated from Langevin or ADO theory. Two exceptions are the reactions with methylamine and nitric oxide where the rate coefficients are smaller by two orders of magnitude.
Planar Lipid Bilayers as Light Guides
Authors: Braun H. P. , Herrmann R. , Michel-Beyerle M. E.
Published: February 2015

The light guide properties of planar lipid bilayers are discussed and experimentally verified. The interaction between the light and the constituents of the bilayer is substantially increased since the light path is as large as the diameter of the film, e.g. of the order of several millimeters. The influence of electric fields on the bilayer and on the bilayer-torus transition region has been investigated. Field induced generation of scattering centers is detected in solvent containing bilayers.
Design of a Chemical Pulse Reactor
Authors: Denzel B. , Seelig F. F.
Published: February 2015

The general reaction X + Y + M → P + M may - due to substrate inhibition at the catalytic site M - give rise to bistability phenomena in an isothermal tubular fixed bed reactor. The parametric conditions for bistability in the single pellet are studied by a numerical technique. Solution of the steady state equations for a two phase model of the tubular reactor shows that narrow zones with high conversion are possible, similar to ignition zones in nonisothermal catalytic reactors. By a cyclic operation with alternating periods of charging the catalyst phase with substrate and discharging it by chemical reaction, pulses of high product concentration can be generated at the reactor outlet. This is demonstrated by simulation of the system assuming low flow velocity as it is characteristic for reaction columns with liquid mobile phase.
A Contribution to the Investigation of T2-Relaxation with a Microwave Pulse Spectrometer
Authors: Schrepp W. , Bestmann G. , Dreizler H.
Published: February 2015

The T2-relaxation of the 220-211 rotational transition of ethylene oxide in different vibrational states, the 13C-isotope and the perdeuterated species has been investigated by a microwave pulse spectrometer. Qualitative arguments for an explanation of the results in terms of relaxation matrix elements are given.
Die Kinetik des Zerfalls von Ditertiärbutylperoxid bei hohen Drücken und Temperaturen / The Kinetic of the Decomposition of Di-tertiary-butyl-peroxide up to High Pressures and Temperatures
Authors: Buback M. , Lendle H.
Published: February 2015

The decomposition of di-tertiary-butyl-peroxide dissolved in n-heptane has been measured ir-spectroscopically up to pressures of 2300 bar at temperatures between 140 °C and 200 °C. The reaction follows a first order rate law with an activation energy Ea = 151.4 ± 1.6 kJ mol-1 and an activation volume ΔV ǂ = 10.1 ± 1.1 cm3 mol-1. The effectivity of the peroxide decomposition is discussed.
Über des magnetische Verhalten von Cs2MYbF6 (M = Na, K, Rb) und Cs2NaYbBr6 / On the Magnetic Behaviour of Cs2MYbF6 (M = Na, K, Rb) and Cs2NaYbBr6
Authors: Urland Werner
Published: February 2015

The magnetic behaviour of Cs2MYbF6 (M = Na, K, Rb) and Cs2NaYbBr6 has been studied in the temperature range between 3.5 and 251.3 K. The magnetic data are interpreted by means of a previously developed model in which the influence of the crystal field is theoretically described by the angular overlap model. The obtained values of the angular overlap parameter eσ(R) for the individual compounds are discussed and compared with each other. The energy values of the crystal-field levels of the 2F7/2 ground state are calculated.
Condensed Aromatics. Part V
Authors: Cyvin S. J. , Brunvoll J. , Cyvin B. N. , Mastryukov V. S.
Published: February 2015

The five-parameter approximation is applied to a normal coordinate analysis of the in-plane molecular vibrations of naphthacene. Vibrational frequencies and mean amplitudes of vibration are reported. The mean amplitudes of vibration for the nonbonded CC distances are studied in particular on the basis of data for benzene, naphthalene, anthracene, pyrene, coronene and naphthacene. The distance types are classified, and characteristic values for the mean amplitudes of the corresponding distances in different molecules are detected.
Equivalence to Thermodynamic Functions Induced in Nonlinear Systems by Symmetries of Transformation Groups
Authors: Busse H. G. , Havsteen B.
Published: February 2015

Characteristic functions have been defined in nonlinear autonomous systems. These functions possess properties which are equivalent to those of the energy and the entropy concepts of thermodynamics. The new functions are induced in nonlinear systems by one parameter transformation groups. The mathematical treatment is based on canonical forms and their transformation.
On the Distribution of Major and Trace Elements Between Metal and Phosphide Phases of Some Iron Meteorites
Authors: Jochum K. P. , Seufert M. , Begemann F.
Published: February 2015

The concentrations of Fe, Ni, Co, P, Cu, Ga, Ge, Mo, Ru, Rh, Pd, W, Ir and Pt in the phosphides and the metal of the coarse octahedrites Campo del Cielo, Canyon Diablo, Cranbourne and Sardis, the coarsest octahedrite São Julião de Moreira and the hexahedrites Braunau and Lombard have been determined by spark source mass spectrometry. Striking differences are observed of the element contents between bulk meteorite and the phosphides as well as between the different phosphide modifications schreibersite and rhabdite. Extreme values are a 20 fold depletion of Ga and a 40 times higher content of Pd in the phosphides. A particularly strong correlation between the noble metal element content and size of phosphide aggregates is observed; it is shown that this correlation is not an artifact of the sample preparation but that is must be real.