bluuebunny/crossref_metadata_2025_split huggingface dataset:
Axial Channeling in Electron Diffraction
Authors: Ichimiya A. , Lehmpfuhl G. 
Published: February 2015

Abstract
Kossel patterns from Silicon and Niobium were obtained with a convergent electron beam. An intensity maximum in the direction of the zone axes [001] and [111] of Nb was interpreted as axial channeling. The intensity distribution in Kossel patterns was calculated by means of the Bloch wave picture of the dynamical theory of electron diffraction. Particularly zone axis patterns were calculated for different substance-energy combinations and they were compared with experimental observations. The intensity distribution in the calculated Kossel patterns was very sensitive to the model of absorption and it was found that a treatment of the absorption close to the model of Humphreys and Hirsch [Phil. Mag. 18, 115 (1968)] gave the best agreement with the experimental observations. Furthermore it is shown which Bloch waves are important for the intensity distribution in the Kossel patterns, how they are absorbed and how they change with energy.
Superstructures on Spherical Gold Crystals
Authors: Melle H. , Menzel E. 
Published: February 2015

Abstract
Spherically shaped crystals of gold were grown by solidification of a drop of melt in UHV. Their surfaces were investigated in situ by RHEED. The superstructures (001) (5 × 20) and (110) (1 × 2) were observed again. Further superstructures were found: on (001) vicinal planes, (227) (1 × 1), (111) (23 × 1) and (551)c(1 × 1). Several of the new structures are related to structures already known.
Steric Interaction of Fluid Membranes in Multilayer Systems
Authors: Helfrich W. 
Published: February 2015

Abstract
The out-of-plane fluctuations of fluid membranes are sterically hindered in multilayer systems. The repulsive interaction associated with the steric or excluded-volume effect is studied theoretically by two methods. The interaction energy per unit area of membrane is derived as a function of temperature, membrane curvature elasticity and mean membrane spacing; it is inversely proportional to the square of the latter. Steric repulsion is estimated for lecithin bilayers in water. There and in other cases, it may compete with van der Waals attraction.
Analysis of X-ray Diffraction Line Broadening using a Non-ideal Standard Specimen
Authors: Keijser Th. H. de , Mittemeijer E. J. 
Published: February 2015

Abstract
In practice a standard specimen used for the elimination of instrumental broadening, by deconvolution, is never ideal. The instrumental line profile always contains some additional broadening due to finite particle size and distortion present in the standard specimen. Further it is sometimes unavoidable to use a standard specimen of a material different from the material to be analyzed, leading to reflections at incorrect sin θ-values (different spectral broadening). Firstly the effect of these deficiencies on the Fourier coefficients of the pure line profile is analyzed. Secondly the consequences for size-strain analysis are considered.
A correction [Eq. (3.4) ] for the difference in spectral broadening between the exact and the approximate instrumental line profile is given. To avoid serious errors, this correction should be performed before particle size and strain are determined according to the so-called Warren- Averbach analysis. Accurate relative determinations of size and strain are possible even in the case that the line profile under investigation and the line profile of the reference specimen are at different sin θ-values. It is suggested that standard specimens which cause noticeable structural broadening can be used profitably.
Ab-Initio and PCILO Calculations of Diamond Clusters and the Corresponding Saturated Hydrocarbons
Authors: Waschi H. P. , Stoll H. , Preuß H. 
Published: February 2015

Abstract
Closed-shell diamond clusters and saturated hydrocarbons are investigated with PCILO and ab-initio Hartree-Fock using very small basis sets. The ab-initio distances for the C-C bonds differ by 5% or less, the PCILO distances by 2 to 2.5% from experimental data. The dependence of bond lengths and force constants on the cluster construction is studied. For selected molecules the effect of intermolecular rotations on the total energy is considered.
Einflüsse para- und diamagnetischer Substanzen auf 1HT1-Relaxationszeiten von Alkoholen / Influences of Para- and Diamagnetic Substances on the 1HT1- Relaxation-time of Alcohols
Authors: Sterk H. , Kalcher J. 
Published: February 2015

Abstract
The homologous series of Alcohols from Butanol to Tetradecanol was investigated with para-and diamagnetic shift-reagents with regard to their influences on the 1H relaxation-times. For the protons of the OH-, the CH2-O-, and the (CH2)n-groups, with increasing distance from the shiftmolecule, a decreasing influence on the T1-relaxation times could be verified. The Methylgroups of the long-chained Alcohols show an inverse tendency which can be explained by paramagnetic and Dipole-Dipole-Interactions with neighbour-complexes.
The purely paramagnetic influence on the T1-relaxation times of the different protons may be obtained by subtracting the diamagnetic influence from the total.
Oxygen Isotope Effect on 31P NMR Spectra in the Phosphate Ion
Authors: Lutz O. , Nolle A. , Staschewski D. 
Published: February 2015

Abstract
By Fourier transform high resolution NMR spectroscopy the 31P signals of the phosphate species 31P16O4-n
18On
3- (n = 0, 1, 2, 3, 4) have been resolved in aqueous solutions of potassium phosphate. An isotope effect on the Larmor frequency of δ(31P) = (0.019 ± 0.002) to lower frequency was found for the substitution of a 18O atom for a 16O atom in the phosphate ion.
Erzeugung und Untersuchung des Cyclopentadienons mit der Methode der temperaturabhängigen Photoelektronenspektroskopie / Preparation and Investigation of Cyclopentadienone by Variable Temperature Photoelectron Spectroscopy (VTPES)
Authors: Eck Veit , Lauer Günther , Schweig Armin , Thiel Walter , Vermeer Hans 
Published: February 2015

Abstract
Using our VTPES technique cyclopentadienone is generated in the gas phase at 500-600 °C from the three different precursors cyclobutene-3,4-dicarboxylic acid anhydride, o-phenylene sulfite and o-benzoquinone and its PE spectrum is recorded. The PE spectrum and also the PE spectra of the various precursors as well as of the cyclopentadienone dimer are interpreted on the basis of our recently developed PERTCI method (i. e. performing large scale perturbation configuration interaction calculations in connection with selection procedures). The agreement between measured and calculated ionization potentials is good.
Density, Viscosity and Dielectric Constant of Aqueous Solutions of Triglycine and Tetraglycine
Authors: Bonincontro A. , Cametti C. , Sesta B. 
Published: February 2015

The density, viscosity, static dielectric constant and microwave dielectric loss of aqueous solutions of triglycine and tetraglycine have been studied at various temperatures from 0 to 60 °C.
A very similar electrostrictive effect is observed for triglycine and tetraglycine solutions, indicating a different conformational behaviour of the two peptides in solution. The density B-coefficients decrease with temperature and suggest solute-solvent interactions which are also supported by the viscosimetric results. The viscosity 5-coefficients are always positive and the sign of dB/dT indicates that the two peptides are structure-breaking molecules.
The dielectric data show the existence of extended hydration sheaths with a different thermal stability for the two peptide molecules. The dielectric relaxation times and the activation enthalpies for these processes are estimated.
Structure of the Molten 37 a/o Cu-63 a/o Sb Alloy Using the Isotopic Substitution Method in Neutron Diffraction
Authors: Knoll W. , Steeb S. 
Published: February 2015

A neutron diffraction study of the eutectic Cu-Sb-melt containing 37 a/o Cu has been performed using isotopically enriched samples. The three partial structure factors describing the Cu-Cu, Cu-Sb, and Sb-Sb correlations have been determined as well as a second set of partial structure factors relating to the distance correlation of fluctuations in number density and concentration.
Unsmoothed total structure factors were used. By Fourier-transformation the corresponding pair correlation functions were obtained. A strong segregation tendency was found. Concentration fluctuations with a correlation length of 2.4 Å could be determined. From the Fourier-transform of SCC the product N̄1α1 was obtained confirming the segregation tendency. The distance of nearest Cu-Cu neighbours in the eutectic Cu-Sb melt was found to be smaller than in pure molten Cu, whereas the Sb-Sb distance is larger than in pure Sb.
According to Faber-Ziman theory the electrical resistivity was calculated and compared with experimental data.
Turbulent Spatio-Temporal Dynamics in Reacting-Diffusing Systems: Results for a Soluble Model
Authors: Ortoleva P. , DelleDonne M. 
Published: February 2015

A class of soluble three "species" reaction-diffusion type systems is presented Exact solutions are obtained which show turbulent spatio-temporal evolution All homogeneous evolution tends asymptotically toward an attractor which is shown to be a two layered two dimensional manifold in the three dimensional species space. Sustained aperiodic spatio-temporal solutions are also found.
By considering particular model systems we show that turbulent solutions may exit as finite amplitude instabilities or as bifurcations which are aperiodic arbitrarily close to the bifurcation point and hence do not arise as a transition starting out essentially periodically.
A perturbation scheme is used to show that d parameter families of spatio-temporal evolution are admitted by more general systems with attracting d dimensional manifolds in the homogeneous chemical kinetics
On the Validity of the Master Equation for Finite Closed Systems
Authors: Seeberg O. 
Published: February 2015

Abstract
Two equations for the macroscopic part W of the statistical operator are considered:

It follows from the physical equivalence of the solutions together with a stability assumption and the assumption that there is a time τ* after which also the derivatives of the solutions are equivalent, that τ* is the life-time of the kernel K and that

Conversely, the equivalence of the solutions follows from assumptions on the life-time of the kernel K together with a stability assumption and a smoothness assumption on the initial statistical operator W(0).
X-Ray Diffraction Profiles of Inhomogeneous Binary Solids
Authors: Schattschneider P. , Wagendristel A. 
Published: February 2015

Abstract
A general expression for x-ray interference profiles of a binary alloy showing crystals of different concentration and thus different lattice dimensions is deduced. This expression contains previously reported relations as special cases, which are discussed briefly. It is not restricted to systems of total solid solubility or cubic lattice.
Molecular Vibration Analysis of the TeCl4 Tetramer and Monomer and the SeCl4 Tetramer
Authors: Cyvin S. J. , Cyvin B. N. , Brockner W. , Demiray A. F. 
Published: February 2015

Abstract
The molecular vibrations of (TeCl4)4 and (SeCl4)4 are studied on the basis of a cubane-like Td model. Symmetry coordinates are produced by using the theory developed for tetrahedral complexes with trigonal ligands. Approximate vibrational frequencies are calculated from very simple four-parameter force fields and used as an aid in tentative assignments of observed frequencies from literature. Next the force fields are refined by adjustments to the observed frequencies assigned as fundamentals. Potential energy distribution terms and mean amplitudes of vibration are calculated. Finally the monomeric form of TeCl4 is analysed, mainly in order to show the frequency shifts on passing from the monomer to tetramer.
MINDO-FORCES Calculation of the Benzyl and Vinyl Radicals and the Reactions 1CH2 + H2 → CH4 and CH4
.+ → CH3
+ + H
Authors: Khalil Salim M. , Shanshal Muthana 
Published: February 2015

Abstract
The MINDO/3-F0RCES method is applied for the calculation of the 1CH2+H2 → CH4 reaction. The variation of geometry is carried out in such a manner as to allow for the deviation from the C2v symmetry along the H7 -CH2 reaction coordinate. The changes in the geometric parameters of the system during the reaction are followed. It is found that the transition state of the reaction corresponds to R = 1.8 Å and has a geometry closer to the reactants than the products. The calculated activation energy is 13.57 kcal/mol and the calculated reaction enthalpy 106.36 kcal/mol (118.9 kcal/mol exp.). Similar calculations for the CH4
.+ yield a D2d structure and a ⊿Hf value of 269.68 kcal/mol (274.0 kcal/mol exp.). The activation energy of the decomposition reaction CH4
.+ → CH3
+ + H· is 84.54 kcal/mol, the reaction enthalpy is 42.83 kcal/mol (38.10 kcal/mol exp.). Using both MINDO/2- and MINDO/3.FORCES a C2v geometry is calculated for the benzyl radical. The ⊿Hf values are 48.40 and 67.93 kcal/mol respectively. The latter calculation shows that the rotated perpendicular conformation of the methylene group is by 2 kcal/mol less stable than the planar one. The rotation transition state corresponds to the rotation angle 50°. The change in ithe geometric parameters during the rotation is followed. For he vinyl radical the MINDO/3-FORCES calculation yields a CCH angle of 151.1° and a Hf value of 69.8 kcal/mol (65 kcal/mol exp.).
On the Chemically Induced Decay Constant Variation of Tc-99 m
Authors: Nagel M. , Brunner G. , Dostal K.-P. , Hartmann E. , Hinneburg D. , Kupsch H. , Pabst D. , Rigó A. 
Published: February 2015

The chemical induced decay constant variations for some complex compounds of Tc-99 m were measured by means of a semidifferential approach, using the scintillation technique. The results are
λ(TcO4
-) - λ(TcCl6
2-) = (2.52±0.30) · 10-3 λ,
λ(TcCl6
2-) - λ(TcBr6
2-) = (-0.02±0.20) · 10-3 λ,
λ(TcCl6
2-) - λ (TcI6
2-) = (0.78 ± 0.41) · 10-3 λ,
λ(TcO4
-) - λ(TcI6
2-) = (3.30 ± 0.30) · 10-3 λ,
λ(TcO4
-) - λ(TcBr6
2-) = (2.50 ± 0.41) · 10-3 λ.
Theoretical estimations by means of atomic structure calculations show that TcO4
- should have the greatest decay constant among the compounds investigated, in accordance with the measured values, and that the decay constants of the octahedral complexes should follow the spectrochemical series, partly confirmed by the experiments.
On Master Operators with Extremal Entropy Production
Authors: Seeberg O. 
Published: February 2015

Abstract
The master operators B which cause the entropy production dH/dt = - k-1 dS/dt to become extremal for fixed statistical operators W are constructed and discussed. There are boundaries of the set B of master operators, B = {B | Σ B2
vu = b} for which the problem is solvable yielding minimal entropy production, while no solution exists in the set B without any constraints. Operators with maximal entropy production must be extremal points of B.
Die Pauli-Gleichung mit Differentialoperatoren für den Spin/ The Pauli Equation with Differential Operators for the Spin
Authors: Kern Eberhard 
Published: February 2015

The spin operator s = (ħ/2) σ in the Pauli equation fulfills the commutation relation of the angular momentum and leads to half-integer eigenvalues of the eigenfunctions for s. If one tries to express s by canonically conjugated operators Φ and π = (ħ/i) ∂/∂Φ the formal angular momentum term s = Φ X π fails because it leads only to whole-integer eigenvalues. However, the modification of this term in the form s = 1/2 {π + Φ(Φ π) + Φ X π} leads to the required result.
The eigenfunction system belonging to this differential operator s(Φ π) consists of (2s + 1) spin eigenfunctions ξm (Φ) which are given explicitly. They form a basis for the wave functions of a particle of spin s. Applying this formalism to particles with s = 1/2, agreement is reached with Pauli’s spin theory.
The function s(Φ π) follows from the theory of rotating rigid bodies. The continuous spinvariable Φ = ((Φx , Φy, Φz) can be interpreted classically as a “turning vector” which defines the orientation in space of a rigid body. Φ is the positioning coordinate of the rigid body or the spin coordinate of the particle in analogy to the cartesian coordinate x. The spin s is a vector fixed to the body.
Optical and Thermal Electron Transfer in KCl: Tl+ Crystals
Authors: Tsuboi Taiju 
Published: February 2015

Abstract
The absorption spectra of Tl2+ in KCl crystals have been measured from 77 to 300 K. Tl2+ gives rise to five absorption bands peaking at 1760, 860, 680, 460 and 233 nm. These oscillator strengths have been calculated. Optical excitation in the 460 nm band destroys the Tl2+ and Tl++ bands and produces the Tl0 bands. Thermal excitation of a crystal containing only Tl2
+ and Tl++ results in the simultaneous decay of Tl2
+ and Tl++.
It is concluded that electrons released from Tl2
+ by optical or thermal excitation are trapped at Tl+ and Tl++. A discussion is given on Tl2
+++: A Tl2
+++ which has an absorption band at 1075 nm is formed when a (Tl+)2 traps a positive hole of a nearby Cl2
-, whereas it is deformed when a Tl2
+++ traps an electron released from a Tl2
+ by optical excitation in the 460 nm band.
Einfluß des Präparationsverfahrens auf das Restwiderstandsverhältnis kleiner Niobkugeln/ The Influence of Preparation on the Residual Resistivity Ratio of Small Spherical Niobium Samples
Authors: Gärtner K. , Westphal M. 
Published: February 2015

Abstract
A technique for preparing spherical niobium samples of high purity is described. The preparation of tunneling junctions starts from such spheres. The influence of temperature gradients during a heat treatment on the sample purity is discussed.
Different Kinds of Chaotic Oscillations in the Belousov-Zhabotinskii Reaction
Authors: Wegmann Klaus , Rössler Otto E. 
Published: February 2015

Abstract
Following earlier evidence for chaotic time behaviour in the open flow continuous stirred Belousov-Zhabotinskii reaction based on a single measured observable, now two-dimensional phase plots are presented. The potential of a bromide ion sensitive electrode was plotted against the electrochemical potential. In the two-dimensional observation space obtained, both apparent limit cycle oscillations and apparent chaotic oscillations were observed. Of the latter, type 1 resembles a double-limit cycle system with fluctuation-triggered transitions between the two regimes (exogenous chaos); type 2 is analogous, but here the irregular transition between the two oscillatory regimes gives the impression of being, in principle, independent of exogenous noise. If so, this flow may be related to one of the chaotic flows with saddle point known (for example, the Lorenz attractor). Type 3, only observed as a transient so far, looks like a two-dimensional projection of screw type chaos, which is one of the simplest types of deterministic chaos. Type 4 corresponds either to a fluctuation-triggered monoflop (exogenous chaos) or to folded-strip (spiral) type chaos.
Notizen:Niederfrequente dielektrische Relaxation in Einkristallen von Rubidiumtetrasilberjodid/ Low-Frequency Dielectric Relaxation in Single Crystals of Rubidium Tetra Silver Iodide
Authors: Becker Stephan , Schön Günter 
Published: February 2015

Abstract
The low-frequency dielectric absorption of RbAg4l5 single crystals was found to have a maximum at about 1 kHz. It was tried to explain this by considering the occurrence of ordered regions of silver ions in the crystal structure, according to the domain model proposed by van Gool. Some aspects supporting this model are discussed.
Die Uran(IV)-Liganden Wechselwirkungen in den Paramagnetischen Tetra- und (Tris-Cyclopentadienyl) -Halogeniden / Uranium(IV)-ligand Interaction in Paramagnetic Tetra- and (Tris-cyclopentadienyl)-halides
Authors: Aderhold Clemens 
Published: February 2015

The magnetic susceptibilities of the uranium tetrahalides and of the tris-cyclopentadienyluranium- halides were measured from 1 to 300 K by using a Faraday magnetic balance at six applied magnetic fields between 3.50 and 13.1 kOe.
It is found that these compounds do not obey a Curie-Weiß law. Their effective magnetic moments at room temperature show maximally 70% of the moment calculated for the free U4+-ion.
By taking into account spectroscopic data the experimental magnetic susceptibilities can be described by using a modified Van Vleck theory.
Structure of the Hel 43D, 3F-2 3P (λ = 447.15 nm, λ = 447.0 nm) Spectral Line Emitted from a Low-Pressure Linear Discharge
Authors: Drawin H. W. , Ramette J. 
Published: February 2015

=
The line profile of the HeI line at λ447.15 nm has been measured during the ionisation phase and during the afterglow of a condensed low-pressure helium discharge by means of a 10-channel spectrum analyzer having a channel width of 0.1 Å. The temporal resolution was I.6 μs (e-folding time). The filling pressure ranged from one to twenty Torr. The same relative peak structure was observed during the plasma build-up phase and the afterglow, only the intensities of the peaks were different in the two cases. Our measured profiles are quite similar to those obtained under different experimental conditions by other authors who explained the structure as being due to Baranger-Mozer plasma satellites. In contrast to this we did not find any correlation between electron density and peak position, i.e. the interpretation as Baranger- Mozer plasma satellites has to be excluded. The wavelengths of a number of peaks agree well with already identified He2 molecular lines, and there are sufficient experimental indications to conclude that the prominent part of the satellite structure originates from He0 molecular transitions most of which have not yet been identified.
Hyperfine Structure in the Rotational Spectrum of GaBr
Authors: Pfaffe S. , Tiemann E. , Hoeft J. 
Published: February 2015

The hyperfine structure of the rotational transition J = 2 ← 1 in the vicinity of 9.8 GHz was measured. The analysis yielded the following quadrupole coupling constants:
e qv Q (79Br) = 105.78(34) + 0.92 (38) (ν + 1/2) MHz,
e qv Q (81Br) = 88.55(35) + 0.60(32) (ν + 1/2) MHz,
e qv Q (69Ga) = -86 .6 8(30) + 0.36 (24) (ν + 1/2) MHz,
e q0 Q (71Ga) = - 54.58 (25) MHz.
These results are consistent with systematic trends in the group of (III a/VII a)-compounds and remove some discrepencies in the literature.
Tables of Radiative Corrections to Pion Nucleon and Nucleon-Nucleon Scattering
Authors: Borie E. 
Published: February 2015

Abstract
The importance of radiative corrections to hadron scattering is discussed, and the relevant formulas presented in a somewhat simpler form than has been given previously. Tables are given to enable the experimentalist to estimate the numerical importance of the corrections, or evaluate them by interpolation.
Application of the Model Microfield Method to Stark Profiles of Alkali Metal Resonance Lines
Authors: Mazure A. , Nollez G. 
Published: February 2015

Abstract
Stark widths and shifts of alkali metal resonance lines are calculated by the model microfield method (MMM). The im pact results of Griem for the prevailing electronic broadening are recovered by the unified MMM. Both theories are in close agreement with recent experimental results. It is shown further that the shift values are very sensitive to the line strength values of the involved transitions. The reliability of the experimentally observed regularities through the alkali sequence is next discussed. On the basis of the MMM results these regularities can be understood in term s of the line strengths and frequencies of transitions from the main levels actually involved.
Ratios of Isotopic Frequencies Using HLFS Method
Authors: Ananthakrishnan T. R. 
Published: February 2015

Abstract
Simple expressions involving elements of the kinetic energy matrix are obtained for the ratios of isotopic frequencies in the case of vibrational species, of order two and three, associated with small molecules by employing the high and low frequency separation method and the product rule. The applicability of the method is indicated.