bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photoelectron (HeI) Spectra of Aromatic Thiocarbonyls and Corresponding S-Oxides
Authors: Bernardi Fernando , Colonna Francesco Paolo , Distefano Giuseppe , Maccagnani Gaetano , Spunta Giuseppe 
Published: February 2015

The low ionization energy regions of the photoelectron (He I) spectra of several p-p′-substituted thiobenzophenones (X-C6H4)2CS and of the corresponding S-oxides (sulphines) (XC6H4)2CSO (where X = H , OCH3, CH3, I, Br, Cl and NO2) have been assigned on the basis of perturbational molecular orbital theory arguments coupled with CNDO/2 computations and substituent effects.
For the thioketones, the ordering of the outermost MO's results to be n(S), π7, π6, π5/π4, π3, n(S) being the HOMO; while for the sulphines the two outermost MO’s have π character and correspond to π7 and π6 in the thioketones.
In the light of the above results the different behaviour toward oxidation of these two classes of compounds can be rationalized.
Retarded Integration in Classical Electrodynamics
Authors: Sorg M. 
Published: February 2015

Abstract
The bound and emitted four-momentum of an accelerated point charge is calculated in a direct manner without use of Gauß' or Stokes' integral theorems. This new integration procedure accounts most naturally for the retarded character of the electromagnetic interactions and, if applied to the bound four-momentum, reveals that the asymptotic condition of uniform motion in the distant past can be weakened essentially.
Ion and Water Transport through Ion Exchange Membranes
Authors: Schröter J. , Stormberg H. P. 
Published: February 2015

Abstract
An ion exchange membrane system is considered in which the concentration of the membrane particles is low. With the help of a perturbation procedure the transport equations for ions and solvent, the so called generalized Nernst-Planck equations can be solved up to the first order. Prescribing concentration differences for the ions, a pressure difference and an electrical field as external conditions, the fluxes and densities of ions and solvent, and the pressure within the system are calculated.
Isotropie and Anisotropie Nuclear Magnetic Shielding of 113Cd in Cadmiumhalides, Cadmiumchalcogenides and in Cadmiumcarbonate
Authors: Nolle A. 
Published: February 2015

Abstract
The NMR signals of 113Cd have been observed in powder samples of the cadmium halides CdF2, CdCl2, CdBr2· 4H2O, Cdl2, of the cadmium chalcogenides CdO, CdS, CdSe, CdTe and of CdCO3 . For 113Cd in CdCl2 , CdBr2-4H2O, CdS and in CdSe anisotropics of the nuclear magnetic shielding have been detected. The shielding tensor in these powders is axially symmetric. For the other specimens no anisotropics of the magnetic shielding have been found. The principal values of the magnetic shielding tensor and the shielding constants are given in an atomic reference scale.
Die Reabsorption in Anthracenkristallen im Temperaturbereich 4 < T < 300 K
Authors: Ganz S. 
Published: February 2015

Abstract
Fluorescence spectra and decay curves of pure anthracene crystals in dependence of the emission wave length have been investigated using different exciting frequencies. A computer program using Monte Carlo Techniques is described which simulates absorption, emission, reflection and reabsorption of photons in a crystal. This program allows the calculation of fluorescence spectra and decay curves. By comparing the results of this program with experimental data, it is possible to correct the decay time for reabsorption and to calculate the reabsorption coefficient in dependence of temperature.
Dielectric Relaxation of Aliphatic Ethers in Dilute Solutions
Authors: Hasan A. , Klages G. 
Published: February 2015

Abstract
Dielectric relaxation of nine primary aliphatic ethers - seven symmetric ethers of chain length C6 to C32, one asymmetric ether and one molecule with three ether groups in the chain - has been studied by loss measurements at 11 frequencies between 0.3 and 300 GHz in dilute cyclohexane and mesitylene solutions at 20°C. The absorption curves are shown not to be symmetrical. The main region has been analysed in terms of a symmetric distribution of relaxation times; the high frequency contribution due to the far infrared absorption was always less than 20%. Symmetric ethers show an increasing mean relaxation time and broadening of its distribution with increasing chain length. The spectra of cyclohexane solutions are found to contain additional short relaxation times. Compared with a, α, ω-dichlorides the mean relaxation times of symmetric ethers generally are shorter, which suggests a high mobility around C-O bonds becoming more effective in the unsymmetric ethers and even more so in the chain molecule with two methoxy end groups.
Secondary Ion Mass Spectra of Apatites
Authors: Lodding A. , Larsson S. J. , Odelius H. 
Published: February 2015

Abstract
The detection sensitivities and the possibilities of quantification in the ion probe analysis of microelements in tooth and bone mineralized tissue are limited partly by selective ionization yields, partly by the complicated intrinsic mass spectra of the apatite matrix. Such intrinsic spectra have been recorded for hydroxy-, fluor- and chlorapatite. The limits of analysis have been examined for most of the elements in the periodic table. With a routine SIMS technique developed for the study of mineralized tissues, the lowest concentrations for semi-quantitative measurement have been assessed to lie below 10 wt ppm for at least 20 elements and below 100 wt ppm for another 25 to 30 trace elements in apatites.
Mikroskopisches Modell eines Ionenkristalles mit einem Brown’schen Untergitter. I. Allgemeine Theorie
Authors: Tillmanns C. H. , Merten L. , Börstel G. 
Published: February 2015

The rigid ion model is extended to ionic crystals with a Brownian sublattice. This sublattice is formed by particles which have the possibility to assume at least two positions along a direction overcoming a potential barrier. Such a Debye relaxation process is connected with a spontaneous dipole moment. Taking into account this additional dipole moment in the equation of motion for ionic crystals we get the corresponding equation for ionic crystals with a Brownian sublattice.
In part II of this paper this complex system of equations, which depends on temperature, is solved for a simple model of a diatomic ionic crystal.
Schwingungsspektren der Schwefelringe S8, 34S8, S12 und S12 · CS2 sowie thermodynamische Funktionen der Moleküle Sn (n = 2 — 12) / Vibrational Spectra of the Sulfur Rings S8, 34S8, S12 and S12 · CS2 and Thermodynamic Functions of the Molecules Sn (n = 2…12)
Authors: Steudel Ralf , Mäusle Hans-Joachim 
Published: February 2015

Raman spectra of S8, 34S8, S12, and S12 · CS2 are reported and force constants have been calculated for S8 and S12 using a modified Urey-Bradley force field. The fundamental vibrations and molecular geometries of S8 and S12 have been used for the calculation of thermodynamic functions. The standard entropies, S0
T, as well as the molar heat capacities, Cp, of sulfur species Sn are shown to depend linearly on the molecular size, n, as follows (in J · mole-1 · K-1):
S0
298 = 35.16n + 147.0, Cp(298 K) = 21.00 n - 11.7.
By interpolation entropies for S9, S10 and S11 have been obtained, and these data are used to show that the concentrations of sulfur rings larger than S8 in sulfur vapor must be negligibly small.
Transmission Electron Diffraction Intensities from Real Organic Crystals: Thin Plate Microcrystals of Paraffinic Compounds
Authors: Dorset Douglas L. 
Published: February 2015

Solvent-grown microcrystals of long polymethylene compounds packing in the O⊥ methylene subcell are found to have some of the defect structures seen for crystalline polyethylene. Crystals composed either of rectangular layers or of oblique layers both exhibit the growth around a screw dislocation characterized earlier by other workers. In addition, rectangular layer crystals of orthorhombic n-hexatriacontane give evidence of intralamellar edge dislocations. When rectangular layer crystals of cetyl palmitate are grown from hot ethanol, the same surface corrugations are found as seen earlier for polyethylene and orthorhombic paraffins. Oblique layer crystals have not demonstrated these latter two defect structures. All crystals show evidence of appreciable bending.
As was found to be true for rectangular layers of n-paraffins, bending has some influence on the electron diffraction intensities from an oblique layer. Another important factor is a perturbation due to defects along long chain axes which disrupts the ordered packing of polar regions, and causes incoherent scatter from these regions. In addition, observed screw dislocations give a nonuniform end plane, causing isolation of layers from one another. Diffraction models accounting for bending or isolation of chain layers in an oblique layer both explain the observed near invariance of certain intensities which are due to the coherent scattering from the line grating formed by rows of carbon atoms in the tilted chain aggregate. Forbidden reflections predicted by a bending model are less important than those anticipated by the multiple scattering from a laminated layer model. As these forbidden reflections are mostly identified for multilayer crystals and since crystal structure analysis indicates most of the long chain in a oblique monolayer to be diffracting coherently, the concentration of Reneker-type defects in the centers of chains is probably not great enough to isolate small chain length laminae within a monolayer.
Eine Modellbetrachtung zur Triplettkinetik von Anthracen/Tetracen Kristallen/A Model consideration of the Triplet Kinetics in Anthracene/Tetracene Crystals
Authors: Wolff H. , Schmillen A. 
Published: February 2015

Abstract
Earlier measurements on anthracene/tetracene crystals are now interpreted with a simplified new model of the triplet kinetics. One result is a threefold exponential decay of the delayed fluorescence of both host and guest. The lowest decay rate as function o f the guest concentration yields
the hopping time of anthracene-triplet-excitons τhT = 3.2·10-12 s;
the detrapping rate ρ = 100 s-1,
and the decay rate o f the guest-triplet state βTG = 1250 s-1 .
The model calculations are also in agreement with measurements of other authors [2, 6].
Calculation of CNDO Characters Orders with Account of Virtual Pars Orbital Contributions
Authors: Fratev F. , Polansky O. E. , Nikolov P. 
Published: February 2015

Abstract
The contribution of virtual pars orbitals to the occupied molecular orbitals is taken into account in the CNDO approximation. On this basis a new index ϱ̄L is introduced, which is similar to the character order ϱL in the π-electron approximation. The calculated values of ϱ̄L for the 19 compounds under investigation correlate well with the experimental bond lengths, as well as with a number of other physical and chemical properties.
Notizen:MIND0 /3 -Parameter für die Bindungsenergie von H2/MINDO/3-Calculations of the dissociation of H2
Authors: Fleischhauer Jörg , Raabe G. , Thiele H. 
Published: February 2015

Abstract
The results of an ab initio calculation of the H2- and the exact values of the H2
+-binding-energies are compared with MINDO/3 values. The MINDO/3-parameters are then varied to give an optimal fit of the H2-energies as functions of nuclear distance.
The Microwave Spectrum of Methyl Selenocyanate (CH3SeCN)
Authors: Landsberg B. M. 
Published: February 2015

The microwave spectrum of methyl selenocyanate has been observed for the isotopic species 12CH3
80Se12C14N, 12CH3
78Se12C14N, 12CH3
77Se12C14N, 12CH3
76Se12C14N, 12CH3
82Se12C14N, 13CH3
80Se12C14N and 13CH3
78Se12C14N.
For the main isotopic species, a full centrifugal distortion analysis is reported and internal rotation splittings have been analysed for the ground and first excited torsional states, and also for the ν10 = 1 and ν10 = 2 excited vibrational states. A structure based on a mixture of rs and ro arguments is reported, and also the principal components of the dipole moments.
On the Evaluation of Transport Collision Frequencies I. The Integration of Empirical Data
Authors: Weinert Ulrich , Kratzsch Klaus-Achim , Oberhage Heinz-Rüdiger 
Published: February 2015

Abstract
The computation of the transport collision frequencies is discussed, provided the transfer cross sections are given at least for a discrete set of relative kinetic energies. Numerical investigations show that the most satisfying results are achieved by the use of rational interpolation of the transfer cross sections.
Leistungseinkopplung in ein Plasma erhöhter Elektronentemperatur bei der unteren Hybridresonanz
Authors: Glomski G. , Heinrich B. , Schlüter H. 
Published: February 2015

Abstract
Previous investigations of lower hybrid resonant coupling to plasmas of low collision frequencies and elevated electron temperature are extended to cover a range of some mW to 1500 W of reactive power. Though resonant behaviour is observed throughout, the efficiency of power transfer is lowered when a threshold at about 1 Watt of reactive power is surpassed. Moreover there is a limited decrease of electron density. For high powers saturation in the drop of transfer efficiency is observed.
Neutron Slowing Down with Inelastic Scattering
Authors: Wakil S. A. El , Machali H. M. , Saad E. A. 
Published: February 2015

Abstract
The neutron slowing-down equation in an infinite homogeneous medium with isotropic scattering is solved. The slowing-down kernel is separated into an elastic and an inelastic part. The collision density is expressed in terms of Green’s function of the elastic scattering only. The Greuling- Goertzel (G-G) approximation is used for the elastic scattering kernel, while Volkin’s model is used for the inelastic one. A differential-difference equation for a one-level excited state is solved by Laplace transform. Discussion of the poles obtained in the Laplace inverse shows that there are forbidden zones in which there is no solution. Numerical calculations of the collision density in Fes6 at 922 and 865 kev levels are performed, which give the same behaviour as obtained by Corngold. The average slowing-down time calculated with our approach agrees with Williams’s result in the asymptotic solution.
Atomic Hydrogen in the Mineral Brasilianite NaAl3(PO4)2(OH)4
Authors: Hill Fritz , Lehmann Gerhard 
Published: February 2015

Abstract
EPR parameters for atomic hydrogen in three nonequivalent special positions at the twofold axis of the monoclinic structure of brazilianite, formed by X-ray irradiation at room temperature, are reported. The g-factors are practically isotropic and close to the free electron value, but the hyperfine splittings exhibit considerable anisotropy. One of the centers shows an additional doublet splitting, most likely due to hyperfine interaction with the proton of one of the OH groups. These hydrogen atoms have the highest thermal stability yet reported. With repeated thermal destruction and formation by ionizing radiation one of the centers is rapidly depleted. Thus they must be formed at defect sites, not from the undisturbed OH groups, and trapped near the sites of formation and their thermal destruction must at least in part be irreversible. Possible defects for their formation are discussed.
The Complete Substitution Structure of 1,2,5-Thiadiazole
Authors: Stiefvater Otto L. 
Published: February 2015

Abstract
Double Resonance M odulation (DRM) microwave spectroscopy has been used to determine the complete substitution structures of 1,2,5-thiadiazole and 3,4-d2-1,2,5-thiadiazole. The 34S-, 13C- and 15N-species o f these two “parent” molecules were studied in natural abundance. The structure parameters o f the two parent forms agree to within ± 0.0005 Å and ± 0.02° with the following averaged values:
Distances (in Å)
S - N = 1.6296
C = N = 1.3270
C - C = 1.4167
C - H = 1.0805
Angles (in degrees)
NSN = 99.44
SNC = 106.51
NCC = 113.77
CCH = 126.27
The new data confirm the earlier work on this substance, but the precision o f the structure parameters is improved by a factor of ~ 10. The apparent C-C bond length in the normal species is found to differ by ~ 0.001 A from that in the 3,4-d2-species. Vibrational contributions (⊿Ivib) to the effective changes of the moments o f inertia are determined for the sulphur atom and the near-axis nitrogen atoms as ⊿Ivib(S) = - 0.0017 μÅ2 and ⊿Ivib(N) = - 0.0035 μÅ2.
Energy transfer through collisions has been exploited to overcome traditional difficulties in the identification o f high-J Q-branch transitions o f rare isotopic forms.
Two-Photon Ionization of Polyatomic Molecules in a Mass Spectrometer
Authors: Boesl U. , Neusser H. J. , Schlag E. W. 
Published: February 2015

Abstract
Two-photon ionization of benzene molecules in a mass spectrometer is performed with a tunable frequency-doubled dye laser. The nonlinear ionization is resonantly enhanced by real intermediate rovibronic levels in the S1 state of the molecule. Our results show that stepwise multi-photon ionization is a very selective and versatile ionization source for a mass spectrometer.
Monte Carlo Simulation of the Interfaces Liquid-Crystal and Liquid-Rigid Wall
Authors: Borštnik B. , Ažman A. 
Published: February 2015

Abstract
The structure of liquids at liquid-crystal and liquid-rigid wall interfaces was studied by the Monte Carlo method on systems consisting of either 128 Lennard-Jones atom s or 128 hard spheres. The resulting density profile can serve as a reference for the approximative methods based on the BGYB hierarchy of integral equations. The pair correlation function close to the rigid wall is found to deviate appreciably from the bulk liquid pair correlation function. The maxima and minima of g(r) are more pronounced in the first two layers of atom s close to the rigid wall.
Adsorption of Hydrogen on a Nickel (100) Surface
Authors: Christmann K. 
Published: February 2015

Abstract
The adsorption of hydrogen on a clean Ni(100) single crystal surface was studied in UHV between 120 K and 500 K means of LEED, thermal desorption spectroscopy and work function measurements. H2 chemisorption occurs in two atomic states β1 and β2 with maximum desorption rates (at saturation) at 318 K and 348 K. The activation energy for desorption was determined to be 20 (± 2) kcal/mole for the β1-state and 23 (± 1) kcal/mole for the β2-state, in excellent agreement with previous results. Saturation at 120 K corresponds to a coverage of 0.9 20%).
The initial sticking probability is 0.06 (± 0.01) and the rate of adsorption follows second order kinetics. No additional LEED spots arose from the H overlayer, indicating the absence of long-range order even at 120 K. The work function results clearly show the existence of two different binding states: Whereas the β2-population gives rise to a linear increase by 100 meV (at 120 K) the ß1-state leads to a decrease of ⊿ϕ to a final value of 30-40 meV.
Investigation by X-Ray Absorption Spectroscopy of Platinum Clusters Supported on Zeolites
Authors: Gallezot P. , Weber R. , Betta R. A. Dalla , Boudart M. 
Published: February 2015

Abstract
The onset of the LIII edge of the X-ray absorption spectrum of platinum in F-zeolites involves an electronic transition from core to band levels producing a so-called white line. The spectral area of this increases and the edge position shifts to higher energies, first when the platinum particle size becomes small enough so that the clusters are in the supercages, second when the clusters are covered with oxygen, and third when multivalent cations are introduced in the zeolite. Both features of the absorption edge indicate that under the three above circumstances, platinum becomes more electron deficient. This conclusion had been inferred earlier from the enhanced catalytic activity of Pt clusters in Y zeolites.
Charakterisierung von Silika (Aerosil) Hydrosolen durch Photonenkorrelationsspektroskopie / Characterization of Silica(Aerosil)Hydrosols by Photon Correlation Spectroscopy
Authors: Killmann E. , Eisenlauer J. , Kaniut P. 
Published: February 2015

Abstract
The diffusion of silica(Aerosil)-hydrosols has been studied by photon correlation spectroscopy. For data analysis the method of cumulants, proposed by Koppel, was used. Effects of charge and hydratation of the silica particles and their complicated aggregated structure required an extrapolation to the solconcentration cs = 0 and the scattering angle θ = 0.
The described data analysis combined with the methodical proceeding - using Aerosil aggregates as a model system - shows how to evaluate the diffusion coefficient and its normalized variance. These data of characterization are important for many kinds of aggregated particles in technical applied dispersions.
Chalcogen Interdiffusion in the System Pb(S, Se)
Authors: Leute Volkmar , Böttner Harald , Schmidtke Heinrich 
Published: February 2015

Abstract
From the sulfur-and selenium-concentration profiles recorded by an electron microprobe the chalcogen interdiffusion coefficient of the system Pb(S, Se) is determined as a function of mass fraction cPbse and temperature. Undoped crystals and Pb-or chalcogen-saturated crystals are studied. The dependence of the interdiffusion coefficient on the deviation from stoichiometry shows that in the chalcogen-saturated part of the system the calcogen interdiffusion proceeds via chalcogen interstitials, whereas in the Pb-saturated part of the system the chalcogens diffuse via chalcogen vacancies. For pure PbSe it is shown that these vacancies are doubly ionized. The activation entropy of the diffusion of the chalcogens depends linearly on the ratio of activation enthalpy to solidus temperature.
Dispersion der gekoppelten Wellen beim stimulierten Raman-Effekt in einfachen piezoelektrischen kubischen Kristallen
Authors: Merten L. , Wenk J. 
Published: February 2015

Abstract
Even in the most simple case of cubic piezoelectric crystals with only one polariton branch the problem of coupling of polariton, Stokes and anti-Stokes waves in the parametric approximation leads to six coupled waves, each consisting of a polariton component, a Stokes component and an anti-Stokes component. The dispersion of all six coupled waves can be described by explicit formulae in very good approximation. The shift of the dispersion curves of the coupled waves against the dispersion curves of the uncoupled waves is proportional to the square of the amplitude of the pump wave
UPS Spectra of Cis and Trans 1-Phenyl-2-(4-Pyridyl) Cyclopropanes. A Comparison with Charge Transfer and Protonation Data
Authors: Distefano G. , Modelli A. , Mancini V. 
Published: February 2015

Abstract
The low ionization energy region of the USP spectra of cis- and trans-1-(4-X-phenyl)-2-(4pyridyl) cyclopropanes is assigned by analogy with those of simple related molecules. Corresponding IE values of cis and trans derivatives are equal within the limits of experimental error. This finding indicates, at variance with solution results previously obtained, that in the gas phase there is no sizeable through- space interaction between the MO’s of the two cis-aryl groups. A possible explanation of the different conformations of the cis derivatives in the two phases is proposed
Evidence for Polymorphism within the So-called “Blue Phase” of Cholesteric Esters. I. Calorimetric and Microscopic Measurements
Authors: Bergmann K. , Stegemeyer H. 
Published: February 2015

Abstract
Calorimetric measurements as well as microscopic observations confirm the existence of two thermodynamically stable polymorphic forms of the so-called “blue phase” of cholesteryl nonanoate and myristate
Evidence for Polymorphism within the So-called “Blue Phase” of Cholesteric Esters. II. Selective Reflection and Optical Rotatory Dispersion
Authors: Bergmann K. , Pollmann P. , Scherer G. , Stegemeyer H. 
Published: February 2015

Abstract
In cholesteryl nonanoate the existence of two polymorphic forms of the so-called “blue phase” has been evidenced by selective reflection and optical rotatory dispersion measurements. The spectroscopic results indicate a discontinuous transition between the two phases