bluuebunny/crossref_metadata_2025 huggingface dataset:
Determination of the Composition of TiNx and TiBxNy Films by AES
Authors: Baker M. A. , Haupt J. , Gissler W.
Published: February 2015

For the determination of x and y of TiNx and TiBxNy coatings two Auger methods are presented, one circumventing and the other minimising the difficulties arising from the overlap of the KL23L23 and L3M23M23 peaks of N and Ti, respectively. The first method, developed for TiNx coatings, is based on the L3M23M45 valence band peak of Ti which develops a distinct second peak on nitridation, 3.9 eV below the main peak, labelled the L3M23Hybrid peak. After a simple Shirley background correction, a linear dependence of the L3M23Hybrid/L3M23M45 peak height ratio on the N/Ti ratio was found. This allows the determination of the N content of a TiNx compound. For TiBxNy coatings, a more complex shape of the L3M23M45 peak is obtained due to the presence of more than one phase, rendering this peak unusable for quantification. Therefore the N/Ti ratio is obtained from the L3M23M23/L3M23M4, peak intensity ratio for Ti. To minimise influences of the fine structure and improve the accuracy of the method, the negative peak excursions were artificially broadened. The N/Ti ratio so obtained is used in combination with the B concentration determined from the KL23L23 peak of B to yield the Ti-B-N composition.
Molecular Motion in Liquids: The Partially Rigid Molecule 1,2,3,4-Tetrahydro-5,6-Dimethyl-1,4-Methanonaphthalene. Temperature Dependence of 13C Magnetic Relaxation and Correlation Times
Authors: Schlenz U. , Dölle A. , Hertz H.G.
Published: February 2015

For the hydrocarbon 1,2,3,4-tetrahydro-5,6-dimethyl-1,4-methanonaphthalene (5,6-Me2-THMN) 13C longitudinal relaxation times and NOE factors were measured over a wide temperature range at frequencies of 22.63 and 100.62 MHz. Additionally, 13C transversal relaxation times were measured at 100.62 MHz. The relaxation data show that the dispersion region is already reached at moderate temperatures. The experimental data were modeled by the combination of the Vogel- Fulcher-Tammann ansatz and a scaling of the dipolar coupling constant with a factor of 0.70. From the fit of the data also activation parameters of the rotational motion of the molecules were obtained. Although the molecules of 5,6-Me2-THMN have a rigid structure (except the two internally rotating methyl groups), the model of the rotational diffusion of rigid bodies does not satisfactorily describe the relaxation data.
Diffusive Motion in Stage-1 and Stage-2 Li-Graphite Intercalation Compounds: Results of ß-NMR and Quasielastic Neutron Scattering
Authors: Schirmer A. , Heitjans P.
Published: February 2015

Investigations of Li diffusion in stage-1 and stage-2 Li graphite intercalation compounds with neutron time-of-flight and backscattering techniques and β-radiation detected nuclear magnetic resonance/relaxation (β-NMR) with the nucleus 8Li(T1/2 = 0.8 s) are reviewed and compared. Depending on temperature, the spin-lattice relaxation-rate T1
-1of 8Li is governed by different processes. Above 300 K, T1
-1 (T) shows maxima induced by long-range Li+ diffusion. Jump correlation times are estimated. Inspection of the B field dependence of T1
-1 revealed two-dimensional diffusion behaviour. The neutron spectra showed a quasielastic line broadening above 500 K, which was used to obtain diffusion coefficients and to trace jump vectors of the in-plane motion. The diffusion parameters observed with both techniques are compared, and differences that show up are discussed. In addition, the low-temperature spin-lattice relaxation rates, being due to coupling to conduction electrons, are used to explore electronic properties.
Physical Chemistry of Hydrogenous Species in the Si-Si02 System
Authors: Poindexter Edward H.
Published: February 2015

Research on hydrogenous species in the Si-Si02 system is reviewed and examined. Some aspects of thermal silica on silicon are explained by comparison with crystalline quartz or bulk amorphous fused silica. Hydrogen behavior in the Si-Si02 system is complicated by the unique features of device processing technology, an electrified interface, and high electric fields. An electrochemical model of the negative-bias-field-induced degradation of the system is used as a starting point for discussion of diffusion and solubility, atomic H disposition, thermochemical phenomena, and radiation damage. It is thereby hoped to provide new approaches for complete modeling of hydrogen physical chemistry in the Si-Si02 system.
Wiener Indices and Molecular Surfaces
Authors: Gutmana Ivan , Körtvélyesi Tamás
Published: February 2015

A correlation between the Wiener index (W) and the molecular surface of the respective alkane is established for the first time. This correlation is curvilinear and not particularly good. W is only weakly correlated to molecular volume of saturated hydrocarbons and does not reflect at all their surface-to-volume ratio. By this a long-existing controversy concerning the physico-chemical interpretation of W is resolved.
An X-Ray Diffraction Study on Amorphous Transition Metal-Boron Alloys Obtained by Different Preparation Methods
Authors: Corrias Anna , Ennas Guido , Paschina Giorgio , Zedda Daniela
Published: February 2015

The metal-metal structure of amorphous metal-boron alloys prepared by melt spinning, chemical reduction and mechanical alloying is compared. The general features of the structure functions and radial distribution functions obtained from X-ray diffraction data are similar. The first peak of the radial distribution function, mainly due to metal-metal nearest neighbours, has been simulated by a peak shape function. In all the investigated samples the best fit was obtained using two slightly different metal-metal distances, which suggests the presence of an asymmetric distribution.
Accumulation and bifurcation points of the discontinuous logistic map
Authors: Chia T. T. , Tan B. L.
Published: February 2015

For most values of xd ∈ ( - 1,1), the logistic map with a sectional discontinuity at x = xd possesses at least one inverse cascade. By using the property that, when xd is positive or zero, every first cascade accumulates at a parameter a = aacc immediately at the end of a 2-cycle, we explain the functional dependence of aacc on xd. Further, we derive hitherto unknown, general analytical expressions for aacc when xd lies in the range (0,0.9); in particular, these expressions give values of aacc identical to those previously found by a computational technique for selected values of xd in the same range [B. L. Tan and T. T Chia, Phys. Rev. E 47, 3087 (1993)]. We also present a method for calculating the values of the bifurcation points within any inverse cascade for this map and for the TB map which consists of two piecewise linear portions [A. S. Lima, I. C. Moreira, and A. M. Serra, Phys. Lett. A 190, 403 (1994)].
Algebraic Solution of the Coincidence Problem in Two and Three Dimensions
Authors: Baake Michael , Pleasants Peter A. B.
Published: February 2015

The coincidence problem is analyzed in an illustrative fashion for some lattices and modules in two and three dimensions which are important for crystals and quasicrystals. We give a complete description of the groups of coincidence rotations with their associated indices and encapsulate their statistics by means of generating functions.
Nonlinear Resonance in Neuron Dynamics
Authors: Rader Scott , Wheeler Diek W. , Schieve W.C. , Das Pranab
Published: February 2015

Hübler's technique using aperiodic forces to drive nonlinear oscillators to resonance is analyzed. The oscillators being examined are effective neurons that model Hopfield neural networks. The method is shown to be valid under several different circumstances. It is verified through analysis of the power spectrum, force, resonance, and energy transfer of the system.
On the Time-Independent Perturbation Theory
Authors: Campos D.
Published: February 2015

The time-independent perturbation theory is developed for an arbitrary operator

which can be expanded in powers of the perturbation parameter λ. A unified formulation allows the establishment of a formal interrelation between the methods of Rayleigh-Schrödinger and of Bril­ louin-Wigner. We introduce a nonunitary transformation operator to connect the nth eigenket of Ĥ(0) with the nth eigenket of Ĥ(λ) and it is proven that this operator satisfies a Lippmann-Schwinger type equation. A perturbation method based on this equation is proposed, and it is applied to describe an electron moving in a Yukawa potential.
Chemical and Topological Short Range Order of Amorphous Ti-Si Alloys
Authors: Pojtinger A. , Bellissent R. , Lamparter P. , Steeb S.
Published: February 2015

Amorphous Ti100 - xSix alloys (13<x<60) were produced by sputtering. Their partial structure factors were determined by X-ray and neutron diffraction. The Bhatia-Thornton density-concentration correlation function GNC(R) was calculated by a cluster relaxation model. Three-dimensional atomic clusters were produced by the Reverse Monte Carlo method. These clusters were analyzed in terms of trigonal prismatic arrangements as a structural unit. In amorphous Ti75Si25 and Ti87Si13 those Si-atoms which are surrounded by 9 Ti-atoms in the first coordination shell prefer trigonal prismatic arrangements. In the atomic clusters of amorphous Ti59Si41, Ti49Si51, and Ti40Si60, however, no preference of trigonal prisms was found.
Die Lösung der Schrödinger-Gleichung als eindimensionales Problem. II. Test an Einelektronatomen
Authors: Preuß H. , Pernpointner M.
Published: February 2015

As announced in part I of this work, concrete calculations on the one-electron atoms H, He+, and Li2+ are presented here. The results allow a comparison between the implemented method of discretization and other methods with respect to the one-dimensional formalism. The use of a Gaussian integral kernel makes it possible to perform the spatial integration analytically. Further­ more it is shown how fast oscillations in the curve parametrization can be avoided by the use of non-integral parameters.
Landau Theory of a System with Two Bilinearly Coupled Order Parameter sin External Field: Exact Mean Field Solution, Critical Properties and Isothermal Susceptibility
Authors: Kornyshev A.A. , Kossakowski D.A. , Leikin S.
Published: February 2015

We present simple description of a system with two bilinearly coupled order parameters in external field based on an exact mean-field solution of the Landau Hamiltonian. It reproduces the qualitative form of the "field-temperature" phase diagram given by a molecular-field model and by more sophisticated theories and experiments on metamagnets. The solution gives the same critical exponents as the molecular-field theory, but it is not restricted to the magnetic systems only and it is easier to handle, since it formulates the results in explicit analytical form. The susceptibility in this model does not diverge at the second order transition line (far from a higher order critical point separating the second and first order transition lines), but jumps down from the lower temperature wing to the higher temperature one. The jump amplitude is proportional to the square of the field in small fields and diverges in large fields close to the higher order critical point.
A Simplified Thermodynamic Theory for Biaxial Nematics
Authors: Papenfuß Christina , Verhás Jozsef , Muschik Wolfgang
Published: February 2015

A continuum theory of a biaxial nematic phase in liquid crystals is presented. The liquid crystalline ordering is described by a field of three unit vectors. Because these are macroscopic directors, the present approach is a generalization of the Ericksen-Leslie theory to biaxial nematics. The applied tools from nonequilibrium thermodynamics are classical Linear Irreversible Thermodynamics and Gyarmati's variational principle.
Comments on the Dynamical Theory of X-Ray Diffraction in Crystals
Authors: Wagenfeld H. K.
Published: February 2015

Von Laue reformulated Ewald's dynamical theory of X-ray diffraction in crystals by solving Maxwell's equations for an electric susceptibility which has the periodicity of the crystals lattice. Absorption was in the original paper not included. Kohler showed that in this case the electric susceptibility is directly proportional to the electron charge density within the crystal.

Von Laue assumed that the divergence of the electric field vector E is equal to the electron charge density which is excited by the electromagnetic field, and this is in accordance with Lorentz' classical electron theory. Under this assumption E is in contrast to D not a transverse wave. This is the reason that von Laue derived the fundamental equations in terms of D, and in order to obtain a simple wave equation he used the approximation 4πP = ϰD. Here P is the vector of the electric polarization and ϰ is 4π times the electric susceptibility. This approximation is well justified, and von Laue's formulation is used in most publication on this subject.

However some authors derived the fundamental equations in terms of fusing the correct relation 4πP = ϰE . In most publications they assumed that the longitudinal component of the vector E is small and neglected it. This point and the comparison with von Laue's formulation was discussed by Miyake and Ohtsuki. We show here that the divergence of E can be put zero if inelastic processes are excluded. This follows from Kohler's and Moliere's papers on the wave mechanical foundation of the dynamical theory of X-ray diffraction. However if higher perturbation terms are taken into account then the divergence of E differs from zero.

In multiple beam cases the fundamental equations are much simpler if they are expressed in terms of E. In the region of anomalous dispersion, and here in particular in the region where the X-ray energy is close and above and crystal absorption edge, the wave equations should be expressed in terms of the electric field vector E.
Calculation of Theoretical Alpha Coefficients for XRF Analysis of Major and Minor Elements in Iron-rich Geological Samples
Authors: Hua Younan , Yap C. T.
Published: February 2015

This paper introduces a method of calculating theorectical alpha coefficients for the X-ray fluorescence analysis of major and minor components in iron-rich samples. We choose a group of hypothetical standard samples whose average concentrations are those of the actual samples. The theoretical X-ray fluorescence relative intensities of the given components are calculated using the fundamental parameter NRLXRF program. We derived formulas from the Lachance-Traill equation and used these to calculate the basic, hybrid and modified alpha coefficients which are used respectively for the analysis of elements in compact specimens, oxides in compact specimens and oxides in diluted specimens. In order to use the theoretical alpha coefficients on-line, we also discuss the calculation of the alpha coefficients used in the D.J model.
Rotational Resolution in the VUV-Spectrum of CF3I via Infrared-Ultraviolet Double Resonance Experiments
Authors: Bahnmaier Albert H. , Jones Harold
Published: February 2015

This paper reports the double resonance signal observed by combination of a cw CO2 laser with a pulsed uv ionisation technique (REMPI). The infrared laser was used to pump a single ro-vibrational transition of the ν1 band of CF3I, and the resulting change in the two-photon, vuv spectrum was observed. Signals were detected under conditions of mass selectivity using a time of flight mass spectrometer.

Previously unpublished data from infrared-microwave double resonance experiments are also included.
Dynamics of Nitrite Ions in the Ionic Plastic Crystal TINO2 studied by 15N and 205TI NMR
Authors: Honda Hisashi , Ishimaru Shin'ichi , Onoda-Yamamuro Noriko , Ikeda Ryuichi
Published: February 2015

The temperature dependences of the NMR spin-lattice and spin-spin relaxation times and the NMR spectra of 15N in TI15NO2 were observed in the plastic phase (282.4 K < T < 459 K) and the low-temperature phase. From the analysis of 15N NMR data, we attributed the motion reported in dielectric and TI NMR studies in the low-temperature phase to the 180°-flip of NO2
- ions which takes place with an activation energy of 14 kJ mol-1. In the plastic phase, we detected isotropic NO2
- reorientation with an activation energy of 13.5 kJ mol-1 and a new anionic motion with 10 kJ mol-1.
EXAFS Study on the Phase Transition (Phase α’-δ) in CH3NH3I
Authors: Ishida Hiroyuki , Maeda Hironobu , Hirano Akiko , Fujimoto Tamotsu , Kubozono Yoshihiro , Kashino Setsuo , Emura Shuichi
Published: February 2015

The local structure of CH3NH3I around the I- ion in Phase α' and δ was studied by iodine K-edge EXAFS. The crystal structure in Phase α' was redetermined by single crystal X-ray diffraction. The Debye-Waller factor σ(2) derived from EXAFS spectra shows an anomalous behavior around the order-disorder transition temperature from Phase δ to α'. The phase transition has been interpreted as the disordering process which involves not only the H atoms but also the C atoms in the cation.
λ-Transition to the Bose-Einstein Condensate
Authors: Grossmann Siegfried , Holthaus Martin
Published: February 2015

We study Bose-Einstein condensation of comparatively small numbers of atoms trapped by a three-dimensional harmonic oscillator potential. Under the assumption that grand canonical statis­tics applies, we derive analytical expressions for the condensation temperature, the ground state occupation, and the specific heat capacity. For a gas of TV atoms the condensation temperature is proportional to N1/3, apart from a downward shift of order N-1/3. A signature of the condensation is a pronounced peak of the heat capacity. For not too small N the heat capacity is nearly discon­tinuous at the onset of condensation; the magnitude of the jump is about 6.6 N k. Our continuum approximations are derived with the help of the proper density of states which allows us to calculate finite-AT-corrections, and checked against numerical computations.
On the Structure of Moltenand Amorphous Cu84.3P15.7by X-ray Diffraction
Authors: Hagenmayer R. M. , Lamparter P. , Steeb S.
Published: February 2015

The atomic distances in molten Cu84.3P15.7 at 770°C are smaller than those in the amorphous state at room temperature. This follows from the pair correlation functions obtained from the total structure factors. Since the weighting factors are rather inconvenient, it is not possible to draw conclusions concerning short range order in amorphous or molten Cu84.3P15.7.

Small angle scattering with the amorphous specimen shows up regions with a radius of gyration of 14 Å, whose density is different from the surrounding matrix.
Polarized Oxygen Kα and Copper Lα X-Ray Emission Spectroscopy of YBa2Cu3O7
Authors: Kottmann A. , Siebinger R. , Steeb S.
Published: February 2015

The high temperature superconductor YBa2Cu3O7 is characterized by a very anisotropic structure. The electronic structure of this compound is studied using high resolution valence band spectroscopy within an electron probe microanalyzer. From single crystals and melt-textured specimens,orientation dependent Cu-Lα spectra are obtained using a beryl crystal. The Cu-Lα spectra with polarization parallel to the z-direction show a larger energetic breadth compared to those obtained with polarization perpendicular to z. This is caused by occupied Cu3d3z
2-r
2 like states, as could be shown by other workers using cluster calculations.

With a chlinochlore crystal, the polarized O-Kα, spectra can be used to investigate the orientation of single crystal areas. The spectra map the bandlike O2p states. In contrast to the Cu-Lα spectra,the partial O -Kα spectra agree with band structure calculations in the local density approximation done by other workers.
High Resolution NMR Spectroscopy on Whole-Body Imagers:Optimized Single-and Multi-Pulse Experiments in Vitro
Authors: Schick Fritz
Published: February 2015

From 100 ml spherical glass bottles filled with aqueous solutions and suspended in a homogeneous magnetic field, NMR spectra with linewidths of about 0.7 Hz were achieved in single-pulse and multi-pulse spectra. A relatively wide receiver coil as the body coil or the standard head coil of the manufacturer were employed to acquire spectra after different non-localized pulse sequences. Examples of single-pulse spectra and double spin-echo spectra of aqueous solutions with lactate, citrate, or glucose are demonstrated and discussed. The fact that all experiments can be performed using well-defined pulse angles acting on the entire sample at the field strenght of the whole-body unit allows to determine the characteristics (e.g. chemical shift differences, coupling constants) of spin systems of biologically important molecules precisely, without need for additional spectrometers. Constant flip angles are advantageous for adequate theoretical analysis of spectra from coupled spin systems. The effects of a defined "misadjustment" of the transmitter on the spectra can be measured directly, whereas localized methods always yield a superposition of signals due to the distribution of flip angles inside the selected volume. In some cases, optimized sequence parameters for localized examinations in vivo can be derived numerically from the analyzed coupling data.
Absorption Model of Hydrogenic Atoms and Ions by Metal Surfaces
Authors: Erkovitch O.S. , Komarov V.V. , Popova A.M. , Enderle M. , Melsheimer O. , Neumann H.
Published: February 2015

A model of the interaction of thermal atoms and ions with metal surfaces is presented. The model is based on the multi-particle density functional method. This method is applied to describe first the properties of the electron gas on the metal surface and second to analyze the effective potential of the Hydrogenium atom in the vicinity of the metal surface.
Gibbs Transfer Energies of Some Uni-Univalent Salts in Water—N-Methyl-2-Pyrrolidinone Solvent Mixtures at 30°C
Authors: Varadarajan T. K. , Ramakrishna T. V. , Kalidas C.
Published: February 2015

The standard Gibbs transfer energies of some uni-univalent electrolytes like potassium picrate, tetraphenylarsonium picrate, potassium and silver tetraphenyl borate were determined in water + N-Methyl-2-Pyrrolidinone mixtures from solubility measurements at 30 °C. They were split into respective ionic values on the basis of the reference electrolyte method using tetraphenylarsonium tetraphenylborate. The variation of transfer energies of the ions with composition of solvent are examined and discussed in terms of the possible ion-solvent interactions.
Differential Thermal Analysis (DTA) and Dielectric Studies of 4 -(trans-4-Heptyl-Cyclohexyl)-benzonitrile (7PCH) under High Pressure
Authors: Brückert T. , Büsing D. , Würflinger A.
Published: February 2015

With the aid of DTA the phase diagram of 4-(trans-4-heptyl-cyclohexyl)-benzonitrile, 7PCH, was redetermined. Dielectric studies on the static and complex permittivity have been performed on 7PCH in the pressure range 0.1 -220 MPa, the frequency range 1 kHz-13 MHz and the temperature range 290-380 K. For the slow relaxation process in the nematic phase, characterized by the relaxa­tion time tII , we have calculated the activation volume, Δ ≠
V
II, of about 80 to 60 cm3/mol (decreasing with increasing temperature), and the activation enthalpy, Δ ≠
H
II, of approximately 70 kJ/mol. The isochoric activation energy, Δ ≠
U
II, amounts to about 36 kJ/mol. The pressure dependence of Δ ≠
H
II is less pronounced compared with previous findings for 5PCH and 7CB. Estimates of t0 (extrapo­lated from the relaxation time in the isotropic phase) allow the calculation of the retardation factor g
II = tII/t0 that is analysed in terms of theories of Martin-Meier-Saupe and Coffey in order to evalu­ate the nematic potential q. Using data for the order parameter 5 from NMR studies it was possible to determine the strength of the interaction potential in the nematic phase and to check the relation q~S which is valid at p = const., but not at V = const. The results are compared with recent findings for other homologous series.
Study of the Dielectric Properties of 7PCH (4 -(trans -4 -Heptyl-Cyclohexyl)-benzonitrile)
Authors: Urban S. , Gestblom B. , Brückert T. , Würflinger A.
Published: February 2015

The results of dielectric studies of 7PCH (4-(trans-4-heptyl-cyclohexyl)-benzonitrile) in the nematic and isotropic phases are presented. The complex dielectric permittivity, ε*=ε' - i ε", was measured in the frequency range 1 kHz-5 GHz, with the use of an impedance analyzer and a time domain spectroscopy (TDS) set-up. The relaxation times: longitudinal tII, and transverse t^ in the nematic phase, and tis in the isotropic phase, were obtained. They served for calculation of the activation barriers for different molecular rotation processes occurring in both phases. Additionally, the retardation factors g
II and g
^ were calculated. Two theoretical models (Meier-Saupe and Coffey et al.) were applied for tne calculation of the nematic potential q. A critical analysis of accessible literature data on the order parameter S is given. On that basis the relation q - SS is tested. The obtained values of the strength parameter S are lower for 7PCH than for 5PCH. Possible contribu­tions to the total energy barrier hindering the molecular rotation around the short axis in the nematic phase are considered.
Density and Electrical Conductivity of NaCl - CoCl2 and NaCl - NiCl2 Molten Mixtures
Authors: Red'kin A.A. , Salyulev A.B. , Smirnov M.V. , Khokhlov V.A.
Published: February 2015

The density and electrical conductivity of cobalt and nickel dichlorides and their solutions in molten sodium chloride have been measured. The density was measured by a dilatometric method, and the electrical conductivity by an AC technique. The molar volume and equivalent conductance were calculated.
Surface Growth and Oxidation of Soot Particles under Flame Conditions
Authors: Schäfer Th. , Mauß F. , Bockhorn H. , Fetting F.
Published: February 2015

Surface growth and oxidation of soot particles is investigated in premixed counter flow flames. Surface growth rates and soot oxidation rates can be evaluated from the measured appearance rates of soot and the calculated surface growth rates derived from the HACA-mechanism. The dependence of surface growth rates and soot oxidation rates on composition of the gas phase, temperature and “surface concentration” is discussed. A mechanism of soot oxidation accounting for the experimental findings is suggested.
Defect Chemistry of “BaCuO2” II. Transport Properties and Nature of Defects
Authors: Chiodelli G. , Anselmi-Tamburini U. , Arimondi M. , Spinolo G. , Flor G.
Published: February 2015

The charge transport properties of "BaCuO2" with 88:90 (Ba :Cu) cation ratio were characterized by thermopower, electrical conductivity and ionic transport number measurements in a wide range of temperature and oxygen partial pressure conditions.

The nature of carriers is always represented by small polarons due to self-trapping of the electronic holes generated by the oxygen non-stoichiometry equilibrium.

Some anomalies in carrier mobility as a function of temperature are shown not to be related to incomplete ionization of oxygen atoms on interstitial sites
On the Paddle -Wheel Mechanism for Cation Conduction in Lithium Sulphate
Authors: Lundén Arnold
Published: February 2015

A few high-temperature sulphate phases are both plastic crystals and solid electrolytes, the latter because the hindered rotational motion of the sulphate ions enhances the mobility of the cations. This interpretation has been called the paddle-wheel model, and it is obvious that cation migration becomes a much more complicated process in a plastic ionic crystal than in a crystal with a stiff, time-independent structure. Thus, there are strongly enhanced contributions from conventional migration mechanisms, such as jumping from well-defined lattice sites, but it is evident that there also are contributions which are specific for the paddle-wheel mechanism. By the molecular dynamics study by Ferrario, Klein and McDonald it has become possible to identify separately the contributions from centre-of-mass displacements and rotations of the sulphate group. Information in this direction has also been obtained recently by Karlsson and McGreevy in a neutron powder diffraction study where the reverse Monte Carlo method is used for modelling the data. The latter authors have modified the terminology slightly, which causes confusion regarding the meaning of the term "paddle-wheel mechanism". The "paddle-wheel" enhances not only bulk migration but also migration along interfaces and surfaces. The mobility can also be increased for monovalent anions present. Some examples are given of other types of mobility enhancements which also are due to libration or rotation of polyatomic anions.
Nuclear Physics with Antiprotons
Authors: Egidy T. von , Hartmann F.J. , Schmid S. , Schmid W. , Gulda K. , Jastrzebski J. , Kurcewicz W. , Lubinski P. , Pienkowski L. , Trzcinska A. , Hilscher D. , Bohne W. , Goldenbaum F. , Jahnke U. , Polster D. , Rossner H. , Iljinov A. S. , Mebel M.V. , Nedorezov V.G. , Sudov A. S. , Eades J. , Neumaier S.
Published: February 2015

Information on the neutron distribution in the nuclear periphery was obtained by the annihilation of stopped antiprotons and the yield of residual nuclei. The last atomic transitions of the antiproton before annihilation gives complementary results. Properties of very hot nuclei (up to 1 GeV) after annihilation of stopped antiprotons were studied by neutron emission and fission. Absolute prob­ abilities of fission induced by stopped and fast antiprotons were determined. The experimental data are compared with elaborate calculations taking into account the annihilation process, the fast cascade and pre-equilibrium emission, thermalisation, particle evaporation and fission.
Notiz: Dynamic Dielectric Properties of Some Alkylamino Ethoxylates
Authors: Saad A. , Becker U. , Stockhausen M. , Barakat Y.
Published: February 2015

Nine ethoxylated (EO) alkyl amines, (CnH2n + 1) N(EO)x; H(EO)y H, with n = 10 to 16 and p = x + y = 7.6 to 14.5, were studied as pure liquids with respect to their dielectric relax­ ation behaviour over the frequency range 5 MHz to 36 GHz at 20 °C. The broad and structureless dielectric loss spectrum is similar for all samples. It can be described by a main lower frequency spectral component of Havriliak-Negami type plus two minor, higher frequency Debye type components. The relaxation parameters are reported. Dynamic Dielectric Properties of Some Alkylamino Ethoxylates
Sliding Dynamics of the Frenkel-Kontorova Model
Authors: Strunz T.
Published: February 2015

We investigate the dynamics of the Frenkel-Kontorova model with inertia and damping under a uniform driving force.

We consider the dependence of the velocity-force characteristic, and the corresponding sliding states on the damping: In the overdamped limit the asymptotic solution with nonzero sliding velocity is unique and periodic. Periodic solutions and their stability can also be calculated for decreasing damping, where the dynamics is dominated by resonance effects of the underlying potential with the phonon modes of the chain. The asymptotic velocity is not unique, leading to hysteresis in the velocity-force characteristic. In addition to periodic sliding states, which lose stability for decreasing damping, quasiperiodic or spatio-temporal chaotic behavior occurs.
Nonlinear Dynamics in the Ultradian Rhythm of Desmodium motorium
Authors: Chen Jyh-Phen , Engelmann Wolfgang , Baier Gerold
Published: February 2015

The dynamics of the lateral leaflet movement of Desmodium motorium is studied. Simple periodic, quasiperiodic and aperiodic time series are observed. The long-scale dynamics may either be uniform or composed of several prototypic oscillations (one of them reminiscent of homoclinic chaos). Diffusively coupled nonlinear oscillators may account for the variety of ultradian rhythms.
Application of a Generalized Frobenius-Perron Operator Scheme to Multivariate Nonlinear Dynamical Systems
Authors: Stoop R. , Steeb W.-H.
Published: February 2015

The concept of generalized Frobenius-Perron operators is applied to multivariante nonlinear dynamical systems, and the associated generalized free energies are investigated. As important applications, diffusion-related free energies obtained from normally and superlinearly diffusive one-dimensional maps are discussed.
Stable Kink-Antikink Pairs in Bistable Reaction-Diffusion Systems with Strong Nonlocalities
Authors: Christen Thomas
Published: February 2015

We investigate the statics, nucleation, and dynamics of stable kink-antikink pairs (KAP) in a one-dimensional, one-component reaction-diffusion equation with a piecewise linear nonlinearity. The stabilization of the KAP is due to the presence of a strongly nonlocal inhibitor. We find a saddle-node bifurcation of a metastable KAP with a separation proportional to In L, where L is the length of the sample. The KAP becomes globally stable at a characteristic separation proportional to √L. The nucleation of a KAP from the metastable uniform state differs from the case without nonlocality mainly by a change of the activation energy induced by the nonlocality. Furthermore, we investigate the dynamics of the stable KAP in the presence of an external driving force and a diluted density of pointlike impurities; in particular, we derive expressions for the mobility and the average elongation of the KAP.
An Approach to a Generalized Rössler System via Mode Analysis
Authors: Meyer Th. , Bünner M. J. , Kittel A. , Parisi J.
Published: February 2015

We investigate the generalized Rössler system introduced by Baier and Saale. They have linearly coupled additional degrees of freedom to the original Rössler system in order to construct a set of equations which shows maximum instability at an arbitrary dimension N, i. e., N - 2 positive Lyapunov exponents. We present a transformation into a mode picture. It enables a qualitative understanding of the mechanism generating the dynamics of this complex system. The advantages of our approach are demonstrated for the exemplary case N = 5.
Deterministic Continuous Molecular-Dynamics-Simulation of a Chemical Oscillator
Authors: Diebner Hans H. , Rössler Otto E.
Published: February 2015

A macroscopic chemical oscillator involving 3 autocatalytic second-order reactions is simulated microscopically. A deterministic Newtonian simulation involving 1024 particles with a smooth 1/r potential in two dimensions is presented.
Ionic Conductivity in Li2O-Al2O3-SiO2Based Glasses and Glass Ceramics
Authors: Lunkenheimer P. , Gerhard G. , Drexler F. , Böhmer R. , Loidl A.
Published: February 2015

The complex conductivity of lithium aluminosilicate based glasses and glass-ceramics (Zerodur from Schott) has been investigated in a broad range of temperatures (200 K < T < 700 K) and frequencies (10 mHz<v<2.5 THz). The data are presented in terms of the conductivity and the electrical modulus formalisms. The width of the modulus loss peak as measured for the ceramic sample is broader than that determined for its precursor glass. This result is shown to be associated with the considerably smaller dc conductivity of this material.
ESR of Gamma Irradiated Single Crystals of Acetylcholine Picrate and Methoxycarbonylcholine Picrate Hemihydrate
Authors: Birey Mehmet , Zengin D. Mehmet , Aktas Huseyin , Alicilar Ahmet
Published: February 2015

We have observed two radicals in the ESR spectra of γ-irradiated single crystals of acetylcholine picrate and methoxycarbonylcholine picrate hemihydrate. These radicals have been identified as the CH3COOH and -CH2CH2 respectively.
Unusual Absorption and Fluorescence Properties of p-Substituted Stilbenes in Poly (vinyl alcohol) Films
Authors: Kawski A. , Kukliński B. , Nowosielski T.
Published: February 2015

The behaviour of absorbance, fluorescence and emission anisotropy of linear molecules with one double bond, i.e. 4-amino-4'-nitrostilbene (ANS), 4-dimethylamino-4'-nitrostilbene (DNS) and 4,4'-diphenylstilbene (DPS), was examined in polyvinyl alcohol) (PVA) films at different temperatures (293-423 K). The unusual behaviour of absorption and fluorescence properties of the molecules in­ vestigated, similar to those of linear polyenes in PVA, was, however, less pronounced.
Sub-Doppler Spectroscopy of Ammonia Near 570 GHz
Authors: Belov S. P. , Klaus Th. , Plummer G. M. , Schieder R. , Winnewisser G.
Published: February 2015

We have employed the Cologne terahertz spectrometer [ 1,2] to observe Lamb dip and crossover phenomena in rotational spectra at 572 GHz. Because of the large power output of the backward wave oscillators used in the system, no special means are required to induce this saturation effect; the coincidentally reflected radiation from the bolometer present in our quasi-optical absorption cell is sufficient to saturate the υz = 0 sub-group. This effect has allowed the observation of the three previously unresolved hyperfine components of the l4NH3 A ← S, JK = 10 ← 00 transition, and was also observed for the analogous 15NH3 transition in natural abundance (i. e. 0.366 %). These measurements indicate a possible improvement of molecular transition frequencies in the submillimeter region.
Hyperfine Interaction Induced K-type Doubling in the mmw Spectrum of HS33SH
Authors: Saleck Axel H. , Winnewisser Gisbert
Published: February 2015

The rotational spectrum of the disulfane isotopomer HS33SH has been recorded and assigned between 70 and 300 GHz. In the analysis, rotational constants and 33S hyperfine parameters are derived, the latter accounting for nuclear electric quadrupole as well as nuclear spin -rotation hyperfine interactions. The quadrupole constants are in qualitative agreement with a published ab-initio calculation. The electric field gradient principal axes are considerably rotated against the principal inertial axes, giving rise to off-diagonal elements in the electric field gradient tensor. In combination with the very small inertial asymmetry of the molecule, this causes the A'-doubling in the lowest rotational levels to be dominated by the hyperfine structure rather than the inertial asymmetry contributions. By diagonalization of the quadrupole tensor, an estimate for the dihedral angle (η≈94°) can be obtained, in good agreement with a previous value.
Calculations of 14N and 2H Nuclear Quadrupolar Coupling Constants for Liquid Ammonia
Authors: Laaksonen Aatto , Wasylishen Roderick E.
Published: February 2015

Nitrogen (14N) and deuterium (2H) nuclear quadrupolar coupling constants, ϰ(14N) and ϰ(2H), have been calculated for liquid ammonia at 197 K, 232 K, and 271 K, using a combination of molecular dynamics simulations and ab initio molecular orbital calculations. The basis set and cluster size dependence of the calculated results has been examined. The calculated value of ϰ(14N) for liquid ammonia at 197 K, -3.45 MHz, is found to be close to the accepted solid-state value. At 232 K and 271 K, the magnitudes of the calculated values are about 5 - 10% greater: -3.56 MHz and -3.67 MHz, respectively, but still well below the accepted gas-phase value, -4.09 MHz. The calculated values of ϰ (2H) for liquid ammonia are by about 20% smaller than the corresponding values calculated for the gas-phase monomer. On the basis of the calculations presented here and those of previous workers it is clear that the accepted experimental value of ϰ(2H) for solid ammonia-d3 is too small.
Self-Diffusion in Compressed Dimethylether: The Influence of Dipole-Dipole Interaction and Hydrogen Bonding Upon Translational Diffusivity in Simple Fluids
Authors: Heinrich-Schramm A. , Price W. E. , Lüdemann H.-D.
Published: February 2015

Self-diffusion coefficients of dimethylether have been measured as a function of temperature (185-458 K) and pressure (up to 200 MPa) by pulse-gradient field spin-echo NMR. Calculated activation volumes (ΔV*) fall from 15 (10-6 m3/mole) at the highest temperature to 7 (10-6 m3/mole) at the lowest. This trend is in keeping with values for other non-associating liquids. Comparison with self diffusion data for propane and ethanol reveals that the translational diffusivity in dimethylether is influenced by the substance's modest dipole moment (1.3 Debye). The effect is small but measur­able and becomes more pronounced at lower temperatures.
The Nature of the Mn Moment in Laves Phase Compounds: Evolution of the Magnetic Order in Ho1–xYxMn2
Authors: Ritte Clemens , Cywinski Robert , Kilcoyne Sue H.
Published: February 2015

Neutron powder diffraction has been used to study the evolution of long range magnetic order in the pseudobinary CI 5 Laves phase system Ho1-xYxMn2. Particular attention has been paid to the nature of the Mn moment. At Y-rich compositions (x > 0.9) an incommensurate antiferromagnetic structure, similar to that of YMn2 is observed. Transition to the ordered state, as in YMn2, is accompanied by a 5% expansion of the unit cell, identifying the Mn moments, of 2.7 μB, as intrinsic. The magnetic structure of compositions with x<0.7 resembles that of HoMn2 and DyMn2, with only one quarter of the chemically equivalent Mn sites possessing a moment of 0.6 μB induced by the local symmetry of the antiferromagnetically ordered Ho sublattice. Transition to the ordered state is not accompanied by a cell expansion. Between x = 0.7 and x = 0.9 there is no longe range magnetic order, nor is there an expansion of the unit cell, suggesting the total absence of either induced or intrinsic Mn moments. The results indicate that a critical Mn-Mn near neighbour distance of 2.663 Å is necessary to sustain an intrinsic Mn moment in these compounds.
A Study of the Distribution of Sodium Cations in the Zeolites NaX, NaY and ZnNaY Using Carbon Monoxide Adsorption and 23Na NMR Techniques
Authors: Seidel A. , Boddenberg B.
Published: February 2015

The zeolites NaX, NaY, Zn(55)NaY, and Zn(74)NaY were investigated by means of carbon monoxide adsorption and with static and magic angle spinning (MAS) 23Na NMR spectroscopy. The Na+ distribution between the sodalite (ß)- and supercages of the fully hydrated zeolites NaX and NaY were found to agree with XRD results. In the hydrated zinc-exchanged zeolites the Na+ ions almost exclusively populate the ß-cages.

The adsorption isotherms of CO in the dehydrated zeolites were analyzed quantitatively to yield the concentrations of Na+ residing in the supercages. The measured static and MAS 23Na NMR spectra were analyzed by comparing their widths and shapes with simulated central transition patterns and yield, inter alia, the concentrations of Na+ associated with the spectrum components. Arguments are put forward that 23Na NMR of dehydrated zeolites is well suited to distinguish Na+ cations in highly symmetric environments and mobile Na+ species from others located on general positions, but further resolution is hardly feasible.
The Anisotropy of the Molecular Reorientational Motions in Liquid Methanol
Authors: Ludwig R. , Bopp Ph. A. , Zeidler M. D.
Published: February 2015

Nuclear magnetic resonance (NMR) relaxation time measurements on isotopically substituted samples yield a detailed understanding of the molecular reorientational dynamics in liquids. Reorientational correlation times obtained from such experiments are reported for two molecule-fixed vectors in pure liquid methanol. While the reorientational motions of single molecules are nearly isotropic at temperatures below 250 K, at 308 K the reorientational correlation time of the O-H vector becomes 2.3 times larger than that of the O-C vector. Molecular dynamics (MD) simulations give access to the complete correlation functions of the reorientational motions. Correlation times extracted from these functions fit well to the experiment in case of the O-C vector. At low temperatures, however, these times lie markedly above those obtained in the experiment for the O-H vector. Thus, the simulation yields reorientation times for the O-H vector that are, independent of the temperature, twice as large as those of the O-C vector.
Beschleunigung des Stoffaustausches von Gas-Flüssigkeits-Reaktionen durch Schallwellen am Beispiel der Fetthärtung
Authors: Bartsch Achim
Published: February 2015

A method for increasing the mass transfer in gas/liquid-reactions by application of sonic vibration is described. The operating frequencies have been chosen such that the surfaces of the gas bubbles vibrate in resonance. At these operating frequencies (up to 1000 Hz), the damping of sound waves by the bubbly liquid is low, which is important in large-scale applications. Hydrogenation of soybean oil in a bubble column has been carried out as a test reaction. An increase in mass transfer from dispersed bubbles to the liquid in terms of kLaG of up to 36% has been effected by a relatively small amount of sonic power.
Einfluß der Molekülgröße auf Adsorptionsisothermen
Authors: Meyer C. , Hesse D.
Published: February 2015

Using methods of statistical thermodynamics, adsorption isotherms for the description of differ­ent-sized molecules are discussed by assuming the adsorbing surface to be energetically homoge­neous and by neglecting lateral interaction forces between the adsorbed particles. In this case, besides the temperature and the partial pressures, the adsorption process is mainly influenced by a geomet­rical interaction between the coadsorbed molecules which is modeled by a special parameter. Its value can be determined by geometrical considerations as well as by computer simulations.
Photosensitized Reduction of Carbon Dioxide in Solution Using Noble-Metal Clusters for Electron Transfer
Authors: Toshima Naoki , Yamaji Yumi , Teranishi Toshiharu , Yonezawa Tetsu
Published: February 2015

Carbon dioxide was reduced to methane by visible-light irradiation of a solution composed of tris(bipyridine)ruthenium(III) as photosensitizer, ethylenediaminetetraacetic acid disodium salt as sacrificial reagent, methyl viologen as electron relay, and a colloidal dispersion of polymer-protected noble-metal clusters, prepared by alcohol-reduction, as catalyst. Among the noble-metal clusters examined, Pt clusters showed the highest activity for the formation of methane as well as hydrogen. In order to improve the activity, oxidized clusters and bimetallic clusters were also applied. For example, the CH4 yield in 3-h irradiation increased from 51 x 10-3 μmol with unoxidized Pt clusters to 72 x 10-3 μmol with partially oxidized ones. In the case of Pt/Ru bimetalic systems, the improvement of the catalytic activity by air treatment was much greater than in case of monometallic clusters.
X-Ray Diffraction Study of the Solvation Structure of the Cobalt(II) Ion in N,N-Dimethylformamide Solution
Authors: Yokoyama Haruhiko , Suzuki Saeko , Goto Masuo , Shinozaki Kazuteru , Abe Yuriko , Ishiguro Shin-ichi
Published: February 2015

The solvation structure of Co2+ in N,N-dimethylformamide (DMF) has been studied by X-ray diffraction measurements on cobalt (II) and magnesium (II) Perchlorate solutions of the same concen­ tration, using an isostructural substitution method. The radial distribution function revealed three distinct peaks assigned to the oxygen, amido carbon (C1, and nitrogen atoms of six planar DMF molecules in the first coordination sphere around the metal atom. The distance from the cobalt atom to each atom (O, C1, N) is 213,299, and 423 pm, respectively. This indicates that the Co-O-C1 bond angle is 122-123° and the metal atom is close to the O-C1-N plane of the DMF molecule.
MD Simulation of Crystal Growth from Sodium Chloride Melt
Authors: Okada Isao , Nakashima Toshio , Takahagi Yukio , Habasaki Junko
Published: February 2015

Crystal growth on the (100) and (110) faces of sodium chloride from supercooled melt has been studied by molecular dynamics simulation. The growth velocity was considerably higher for the (100) plane (90-100 m/s) than for the (110) plane (transiently 40-50 m/s). Consequently, even from the (110) face, the crystal seems to grow in the [100] direction. Under the present MD conditions, ca. 2 interface layers with a considerable fraction of defects was formed, which means that the surface advances normal to itself without needing steps.