bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared Absorption of Concentrated Aqueous NaClO4 Solutions to High Pressures and Temperatures
Authors: Valyashko V. M. , Buback M. , Franck E. U. 
Published: February 2015

The infrared absorption of the O-D stretching fundamental of HDO in concentrated aqueous (HDO/H2O)NaClO4 solutions up to 20 mole% salt has been measured. The data for the wave-number of maximum absorption, ν̅(max), and for the integrated molar absorptivity B up to pressures and temperatures of 2800 bar and 250 °C, respectively, demonstrate the importance of non-hydrogen-bonded interactions in aqueous perchlorate solutions. A non-continuous dis­tribution of the states of water molecules is clearly evident from the experimental spectra. A band separation using three Gaussian components proves the close similarity between the high-pressure high-temperature vibrational O-D infrared spectra of aqueous perchlorate solutions and the O-D Raman spectra of water and aqueous solutions.
Results of the band separation together with literature Raman data provide some evidence that a transition from “water-like” to “melt-like” behaviour occurs in a fairly narrow concentra­tion region between 10 and 15 mole% salt.
Der Einfluß unmagnetischer Dotierungen auf die ESR-Linienbreite von antiferromagnetischen Verbindungen / The Influence of Non-Magnetic Dopants on the ESR Line Width of Antiferromagnetic Compounds
Authors: Dräger K. , Gerling R. 
Published: February 2015

ESR spectra of doped antiferromagnetic compounds exhibit a concentration-dependent line width ∆B̄(x). We have investigated polycrystalline samples of Cr2O3 doped with Ga2O3 and Al2O3. For temperatures T sufficiently high above the Néel point TN and for concentrations x≦10%, the experimental values of AB show a linear dependence on x.
This behaviour deviates from theoretical predictions based on the method of second moments. Starting with other reasonable assumptions, we have developed a statistical model of resonance that describes ∆B(x) as a linear function of x. Moreover this allows us to deduce that as far as antiferromagnetic Cr2O3 is concerned, the dopants Ga2O3 and AI2O3 are distributed homogene­ously throughout the lattice sites.
Spin-Orbit Coupling in Tetragonal d3 Systems
Authors: Hoggard Patrick E. 
Published: February 2015

Abstract
The complete set of energy matrices for tetragonal d3 systems, including spin-orbit coupling, has been constructed within the framework of the Angular Overlap Model. Examples are presented of the variation in energy of the intraconfigurational (t3
2g) doublets as a function of spin-orbit coupling (appropriate to first row metal ions) and ligand field asymmetry. It is seen that asymmetry in Dq values is much less important than the relative partitioning of Dq into eσ and eπ. The use of spin-orbit matrix elements in the calculation of intensities of spin-forbidden transitions is also illustrated.
Nuclear Magnetic Resonance of 51V inV3 Si and VSi2 at High Temperatures
Authors: Ploumbidis D. , Rünger R. , Bucklisch R. 
Published: February 2015

Abstract
The Knight shift of the 51V resonance has been measured as a function of temperature in poly-crystalline V3Si and VSi2 samples. For the VaSi system the measurements have been extended to the temperature range from 400 K up to 1250 K, whereas for VSi2 the first NMR measurements at all have been carried out, covering the range 300 to 1250 K. The observed 51V Knight shift in VSi2 is negative (K51V (T=272 K) = -0.15%) and tends to zero with increasing temperature.
Equilibrium of EuS with Gas Mixtures of H2S,H2 and CO2
Authors: Hauck J. 
Published: February 2015

Abstract
EuS and EU2O3 powder samples were equilibrated with H2S-H2-CO2 gas mixtures in the temperature range 700-1500 °C. Since the sulfur and oxygen fugacities of the gas mixtures - as calculated from thermodynamic data - can vary by about 107 , EuS of different stoichiometrics may be produced. At higher oxygen and lower sulfur fugacities EuS is oxidized to EU2O2S. The border line between the two phases can be fitted by the equation log(f(S2)/atm.) = 2 log(f(O2)/ atm.) + 48300/T - 9.3 and compared to border lines of other phases of the Eu-O-S system, which can be calculated from thermodynamic data.
Fluorescence from High Vibronically Excited Benzene: a "Channel Three" Problem
Authors: Wunsch L. , Neusser H. J. , Schlag E. W. 
Published: February 2015

Abstract
Gas phase benzene is excited by two-photon absorption at various pressures between 4 and 80 torr. Fluorescence is observed even from states located at excess energies of 3000 cm-1 - 7000 cm-1 , i.e. well above the onset of "channel three". The nonradiative decay rates as estimated from this fluorescence intensity continue the well known shortening of lifetime with excess energy in a monotone fashion and do not show a drastic cut-off as often concluded from previous line-width measurements.
The Influence of Small Monovalent Cations on Neighbouring Hydrogen Bonds of Aquo-Protein Complexes
Authors: Sagarik Kritsana P. , Rode Bernd M. 
Published: February 2015

Abstract
The influence of small monovalent metal ions on hydrogen bonds of aquo-protein complexes is studied on Li+/HCONH2-OH2 as an example. Using results obtained from ab initio calculations with minimal GLO basis sets, the remarkable changes in the hydrogen bond energy and charge distribution, due to metal ion complex formation, are discussed. The metal ion seems to enhance strongly the donor-acceptor interaction of the O ... H-N-C=0 hydrogen-bonded system.
Die Kinetik des Zerfalls von tert. Butylperoxypivalat bei hohen Drücken und Temperaturen / The Kinetics of the Decomposition of tert.Butylperoxypivalate up to High Pressures and Temperatures
Authors: Buback M. , Lendle H. 
Published: February 2015

Abstract
The decomposition of tert. butylperoxypivalate dissolved in n-heptane has been measured ir-spectroscopically in optical high-pressure cells up to 2000 bar at temperatures between 65 °C and 105 °C. The reaction follows a first order rate law with an activation energy Ea = 122.3 ±3.0 kJ · mol-1 and an activation volume ⊿V≠ = 1.6 ± 1.0 cm3 mol-1 .
Cationization by Alkali Ion Attachment in Laser Desorption Mass Spectrometry
Authors: Stoll R. , Röllgen F. W. 
Published: February 2015

Abstract
The formation of quasimolecular ions by alkali ion attachment in laser desorption mass spec-trometry has been investigated by using a CW CO2 laser. For molecules such as sucrose the desorption of preformed ions could be excluded. Evidence is presented for the ionization by alkali ion attachment in the gas phase. Quasimolecular ions of organic salts were found to result from cationization reactions in the gas phase and from surface reactions. Very fast cation exchange reactions have been discovered for salts and acids impinging on alkali ion emitting surfaces.
Ion Formation from Alkali Halide Solids by High Power Pulsed Laser Irradiation
Authors: Jöst B. , Schueler B. , Krueger F. R. 
Published: February 2015

Abstract
Ion formation from alkali halide solids caused by the irradiation of high power (some 108 W/ cm2) pulsed lasers is investigated by means of time-of-flight mass spectrometry (LAMMA®). It is shown that the ions are formed directly from the solid state, several uppermost atomic layers being involved; gas phase interactions are negligible. The ion formation rates, however, are in-compatible with the assumption of a quasiequilibrium phase transition, but should be explained in terms of non-adiabatic rate processes discussed in some detail. The light absorption of the transparent halide crystals is assumed to be initiated by multiphoton absorption - free electron production; the further energy transfer being maintained by rapid polaron-Joule-heating. The data are compatible with this model.
Pulse Radiolysis and Simulation Computation Studies on Acridine Orange in Aqueous Solutions
Authors: Solar Sonja , Solar Wolfgang , Getoff Nikola 
Published: February 2015

Abstract
A combined pulse radiolysis-computer simulation method was applied for the elucidation of the complicated multiple H-attack on acridine orange in aqueous solutions at pH = 1 to 3. The simultaneous formation of three intermediates was established: semiquinone (H-addition on the N-atom of the chromophore group), R--species (reaction on the meso-C-atom) and H-adducts on the aromatic ring carbon. Their superimposed spectra were resolved, the individual extinction coefficients and the rate constants for their formation and decay were determined. The results are of importance in particular for understanding the decomposition of acridine orange applied as sensitizer in various devices for solar energy utilization.
Ab Initio Calculations of the Molecular Structures and the Electronic Properties of Sulfur-containing Compounds: III. Thioacrolein (CH2=CH–CH=S) and Thioglyoxal (S = CH–CH=S)
Authors: Ha Tae-Kyu , Nguyen M. T. , Vanquickenborne L. 
Published: February 2015

Abstract
Results of ab initio SCF calculations on thioacrolein (CH2=CH-CH=S) and thioglyoxal (S=CH-CH=S) are reported. The geometries are optimized by the analytical gradient method using the double zeta (DZ) basis set. The trans conformers of these molecules are calculated to be more stable than the cis conformer by 2.06 and 4.31 kcal/mol, respectively.
Remarks on Concentration Quenching in Chlorophyll
Authors: Bojarski C. 
Published: February 2015

Abstract
A quantitative analysis of fluorescence self-quenching of chlorophylls a and b in ether as well as chlorophyll a in lipid vesicles and liposomes has been carried out. It is demonstrated that concentration changes of the fluorescence quantum yield can be correctly described by a Förster-type excitation energy transfer process between chlorophyll molecules in the monomeric form if part of the transfers leads to energy degradation.
Geometrization of the Lienard-Wiechert Field
Authors: Sorg M. 
Published: February 2015

Abstract
A geometric description of the Lienard-Wiechert field of a single point charge is given. The dual of the Lienard-Wiechert field can be considered as the curvature in a bundle of 2-planes distributed smoothly over space-time. This geometric construction also accounts for the Teitel-boim splitting of the total field into bound and radiative parts: The radiation field can be identified with the curvature in the normal bundle. Various questions concerning potentials and the integrability of the distributions involved are discussed.
Whereas the intrinsic symmetry group for the field is that of the 2-plane bundle, namely SO (2), the normal bundle approach leads to the group SO (1,1) as the internal symmetry group for the radiation field.
Fluorescence Quantum Yields of Laser Dyes Determined by On-Line Computer Evaluation
Authors: Gauglitz Günter , Lorch Alwin , Oelkrug Dieter 
Published: February 2015

Abstract
The determination of relative fluorescence quantum yields has been improved to better than 3% precision by use of a multichannel analyzer and an on-line desk-top computer. The new combined device for data acquisition and handling as well as a new correction procedure are described. Drifts of excitation source and dark current can be omitted. The yields for laser dyes, emitting at short wavelengths, are presented in dependence on excitation wavelength. These results simplify the optimal choice of the pump conditions of laser dyes, which usually are not photostable.
Turbulence Limits in Rotating Plasmas for Isotope Separation
Authors: Hora Heinrich , Hoyle Ian B. 
Published: February 2015

Abstract
With the aim of using rotating plasmas (driven by j x B or E x B forces) for isotope separation, several experimental configurations have been studied and theory has been developed with respect to numerical models, the Alfvén ionization limit, D'Angelo's shear instability, while turbulence was suggested qualitatively only. A more detailed study of the limit of laminar flow is presented taking into account the magnetic anisotropy of viscosity and interaction with neutrals. In all cases of experiments, the Reynold's numbers are below critical values of 10 4 by at least a factor 100. The pessimistic conclusions of Boeschoten for his experiment can there-fore not be shared with respect to the turbulence problems. The published cases of isotope separation by rotating plasmas are then discussed extensively.
Surface-Induced Flexoelectric Domains in Asymmetrically Strong-Weak Anchored MBBA Films
Authors: Hinov H. P. 
Published: February 2015

Abstract
The longitudinal surface-induced flexoelectric domains, previously obtained in symmetrically weak-anchored nematic layers have been further investigated in asymmetrically strong-weak anchored MBBA layers. The threshold voltages indicating the onset of the flexoelectric instabilities are high for thin cells (d = 9 μm, Uth = 10 V) and small for thick cells (d = 150 μm, Uth =1.5 V). Pronounced minima in the curves p vs. d and Uth vs. d, where p is the domain period and d is the cell thickness, were obtained.
The flexoelectric domains were replaced by electrohydrodynamic instabilities only in the case of strong azimuthal anchoring of the liquid crystal layer.
The role of the sign and the value of the dielectric anisotropy, the homogeneity of the electric field as well as the asymmetry in the surface anchoring are discussed in detail.
Potential Energy Distribution in the Presence of Redundancies
Authors: Brunvoll J. , Cyvin B. N. , Cyvin S. J. 
Published: February 2015

Abstract
A theory is outlined for the potential energy distribution in the presence of redundancies. Numerical examples are given for the cage-like molecules P4S3, P4Se3, As4S3, As4Se3 and PAs3S3, for which the molecular vibrations have been analysed previously.
Molecular Orbital Calculations on the Interaction of PF3 and CO with Ni and Cu Atoms
Authors: Itoh H. , Ertl G. 
Published: February 2015

Abstract
The interaction of Ni and Cu atoms with PF3 and CO ligands was investigated by means of ab initio MO calculations. Coupling occurs mainly through the HOMO (8a1 for PF3 and 5 a for CO) levels with the metal 4s and 3dz2 orbitals, if the 3dn-1 4s1 electronic configuration of the metal atom is considered. The estimated M-PF3 bond lengths are 2.0 Å for Ni and 2.5 Å for Cu. Calculations with Ni(3d10) revealed for PF3 a more pronounced electron transfer to the ligand than for CO. The results are consistent with experimental UPS data for mononuclear complexes as well as corresponding adsorption systems. In particular, split-off d-states observed in UPS data for adsorbed PF3 are attributed to the pronounced lowering of the 3d-orbital energy of the metal atom upon interaction with this electropositive ligand.
Investigation of Self-and Foreign Gas Collision-induced Transitions between M-resolved Rotational Levels of OCS
Authors: Mäder H. 
Published: February 2015

Abstract
Four-level MW-MW double resonance experiments on rotational Stark levels j = 0, 1, 2 and 3 of OCS have been performed to investigate transfer of rotational energy by collisions of OCS with OCS, He, Ne, Ar, Kr, H2, N2, O2, and CH3F. Theoretical arguments are given for the interpretation of the experimentally determined η-values by considering Bloch-type equations of an "embedded" four-level system with ±M degeneracy of the energy levels. The results indicate significant deviations from first order dipole collisional interaction.
Polycrystal Scattering Topography, Scattering Tomography and their Perspective Fields of Application
Authors: Yoneda Yasuharu , Chilcaura Yoshinori 
Published: February 2015

A concept of X-ray topography for polycrystalline materials has been proposed. In this method X-rays scattered from a specimen produce the image. Various techniques for this kind of topo­graphy are described and their characteristic features are pointed out; some of these techniques offer the possibility to make tomographic observations.
The new topographic method has been applied to the observation of commercially used alu­minium sheet and of wood (cedar). The discussion is extended to mechanisms of the image forma­tion and the perspective fields of application.
Generation and Proof of Elliptically Polarized X-Rays
Authors: Brümmer O. , Eisenschmidt Ch. , Höche H. R. 
Published: February 2015

Abstract
Using an arrangement being analogous to optics of visible light the phase relation of the mutually perpendicularly polarized wave fields are examined in the Laue case of X-ray diffraction. Bragg reflections at an angle of reflection of about 45° are used as polarizer and analyzer. The different phase relations result from different thicknesses of a wedge-shaped silicon crystal, which is placed between the polarizer and the analyzer and adjusted for the symmetric 220-CuKαl-Laue case. The determined polarization states produced by coherent excitation of both σ-polarized and π-polarized waves in the silicon crystal coincide very well with calculations of the dynamical theory of X-ray diffraction.
Radial Distribution Function of Liquid Sodium
Authors: Reddy M. Rami 
Published: February 2015

Abstract
The radial distribution function of liquid sodium has been studied by considering the integral equation Perturbation Theory of Madden and Fitts for the reference part and the optimised cluster theory for the attractive part of the pair potential. Calculations were carried out for the long range oscillatory potential of Schiff. The calculated results are compared with the molecular dynamics calculations HTA, OCT and with experiment. The agreement was found to be satisfactory.
Absorption of X-rays by Coplanar Four-beam Reflections
Authors: Pacherová O. , Bubáková R. 
Published: February 2015

Abstract
The absorption effect in dispersion and reflection curves is shown for the a and n polarizations and for some wavelengths in the small wavelength interval in which the coplanar four-beam diffraction of x-rays exists. The investigated coplanar Ge[000, 440, 260, 2̄20] reflections appear in a Ge[440, 2̄20] monolithic monochromator working with CoKα1 radiation. It is shown that the absorption not only reduces the intensity in a complicated way but also changes the energy distribution between the participating reflections.
Curved X-ray Trajectories in Nonperfect Crystals
Authors: Dietrich B. , Härtwig J. , Hölzer G. , Kittner R. 
Published: February 2015

Abstract
X-ray trajectories are determined qualitatively and numerically for some one-dimensional deformation gradients by means of Katos geometrical optics. Based on these results the channelization of X-rays and the X-ray contrast are discussed and proved experimetally.
On the Linearity of Certain Coordinate Transformations Including the Lorentz Transformation
Authors: Sjödin Torgny 
Published: February 2015

Abstract
It is shown that, given choices of units and of synchronization in the moving systems which are independent of the time and space coordinates, the linearity of the transformation equations connecting uniformly moving reference systems is a consequence of the fact that the functions deciding the behaviour of moving bodies and clocks are independent of the time and space coordinates ("homogeneity of time and space").
On a Universal Potential Energy Function and the Importance of Ionic Structures for the Ground State of Molecules
Authors: Van Hooydonk G. 
Published: February 2015

Abstract
The Kratzer-Fues-Varshni-V-potential, applied to ionic dissociation energies, is shown to yield rather accurate potential energy curves in the bonding region for H2, HF, LiH, Li2 and LiF. Vibrational levels, calculated by this ionic approximation to the ground state of widely differing molecules, nearly coincide with RKR-data. At the repulsive side of the curve and up to 2re, the agreement with RKR-curves is even better than for Morse's curve, also for the "covalent" molecules H2 and Li2. Calculated spectroscopical constants αe and ωeχe are far better than those calculated with Morse's function. Even the existence of a maximum in the potential curve at larger r-values seems not in confict with an ionic approximation. From the universal character of the function used, it is concluded that a reasonable approximation for the ground state of all molecules considered is one in terms of ionic structures, even for H2 and especially for Li2. According to the present results, the term “covalent bonding” seems to be definitely superfluous, as the usually made distinction between ionic and covalent bonding is more appearant than real.
Consistent Guiding Center Drift Theories
Authors: Wimmel H. K. 
Published: February 2015

Abstract
Various guiding-center drift theories are presented that are optimized in respect of consistency. They satisfy exact energy conservation theorems (in time-independent fields), Liouville’s theorems and appropriate power balance equations. A theoretical framework is given that allows direct and exact derivation of associated drift-kinetic equations from the respective guiding-center drift-orbit theories. These drift-kinetic equations are listed. Northrop's non-optimized theory is dis-cussed for reference, and internal consistency relations of G.C. drift theories are presented.
The Electric Dipole Moments of Methine Dyes – Comparison of Experimental Results with Theoretical Predictions
Authors: Salamon Z. , Skibiński A. , Celnik K. 
Published: February 2015

Abstract
Absorption and emission spectra of methine dyes in polar and nonpolar solvents were measured. From the Stokes shift as a function of solvent polarity the dipole moments of excited singlet states have been estimated and compared with the quantum chemical predictions. Also the π-electronic charge distribution in the ground and first excited singlet electronic states and bond orders of the dyes were calculated. All investigated methines showed an increase in dipole moment upon excitation to the first excited emitting state.
Orientation of the Absorption and Emission Transition Moments of Methine Dyes
Authors: Salamon Z. , Skibiński A. , Celnik K. 
Published: February 2015

Abstract
The emission anisotropics of the fluorescence of the prolate molecules 2[4(N,N-dimethyloamino)-α styrylo]benzothiazol and 2[4(N,N-dimethyloamino)α styrylojbenzoksazol in solvents of different viscosities were measured, yielding information about the rotational motion of the molecules.
The non-linear dependence of 1/r on T/η was confirmed. On the basis of a comparison of experimental and quantum chemical calculations the orientation of the transition moments of the dye molecules is proposed.
Hydration Shell Structures in an MgCl2 Solution from X-Ray and MD Studies
Authors: Pálinkás G. , Radnai T. 
Published: February 2015

Abstract
The results of a molecular dynamics simulation of a 1.1 molal aqueous MgCl2 solution are com-pared with newly performed x-ray measurements. The structural properties of the solution are evaluated from the scattering data by a model fit to the experimental structure function. The comparison on the basis of fit parameters and partial structure functions shows an overall good agreement between experiment and simulation.
Detailed information on the structure of the hydration shells is deduced from the simulation and shown in form of density maps and angular distributions. It is demonstrated that the octahedral arrangement of the water molecules in the first hydration shell of Mg++ is strongly pronounced while it is only indicated in the case of Cl-. A preferential arrangement in tetrahedral directions has been found for the nearest neighbor water molecules around a central water molecule with an asymmetry in respect to lone pair and hydrogen atom directions. In addition, the probability of finding water molecules at a given number of symmetry sites at the same time has been calculated.