bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Origin of the Rotational Barrier in Trimethylene
Authors: Schoeller Wolfgang W.
Published: February 2015

A quantitative assessment of the barrier of rotation in singlet trimethylene is made by an energy partitioning analysis within the MINDO/2 approximation, including 3X3 configuration interaction between HOMO and LUMO. The dominating factors originate from (a) the non­bonding repulsion between 1,3-positioned atoms and (b) the weak attraction between the 1,5- positioned cis-hydrogens in the EE conformation. The energy difference between the EE and EF conformation is lowered by radical stabilizing substituents, such as a CH3 group (attached to the carbon atom bearing one unpaired electron), because one of the unpaired electrons is stabilized in the EF conformation.
Condensed Aromatics. Part IV. The Five-Parameter Approximation and Mean Amplitudes of Vibration
Authors: Cyvin S. J. , Cyvin B. N. , Brunvoll J.
Published: February 2015

Mean amplitudes of vibration from spectroscopic computations for coronene are presented for the first time. Good agreement is found for the results from (a) the simple five-parameter in-plane force field approximation and (b) the more elaborate Califano-Xeto force field. Mean amplitudes from the former method (a) for naphthalene and anthracene are also given.
Notizen: High Temperature Magnetic Susceptibility of Light Rare-Earth Tungstates
Authors: Dar Naseeb , Lai H. B.
Published: February 2015

This paper reports our results on the magnetic suscep­tibility (Χm) of light rare-earth (viz. Ce, Pr, Nd, Sm, Eu and Gd) tungstates in the temperature range of 300 to 900 K. As expected the variation of Χm with temperature obeys the Curie-Weiss law Χm = C/T - θ). The values of the Curie-constant (C), paramagnetic Curie temperature (θ) and magneton number (p) for the magnetic ions of these tungstates have been evaluated. The experimental p values are in good agreement with the theoretical values of p for these ions. Thus it is concluded that the magnetic (4f) electrons remain intact with the respective ions at high temperature and their participation in electrical conduction is improbable. Negative values of θ normally indicate anti- ferromagnetic ordering in these compounds at low tem­peratures; however in these tungstates the crystal field seems to be the prime reason for Curie-Weiss law behaviour and negative values of θ. The magnetic behaviour of light rare-earth tungstates in briefly discussed.
Information Contained in Open Systems by Example of Chemical Reaction Systems
Authors: Decker Ingo
Published: February 2015

Spatially homogeneous chemical reaction systems with one or two intermediate reaction pro-ducts and with autocatalytic reactionsteps are considered. Because of their non-linearities, such open systems show already primitive forms of self-organization. In order to express the "information" contained in the structures occuring, a theory is developped for measuring that quantity by help of a fictive detector: In treating the stochastic reaction kinetics in the Fokker-Planck-equation approximation, expressions are derived for the averaged amount of information one gets by doing a measurement with the detector and for the temporal conservation of the message being detected. This concept is applied to a one-component reaction scheme that exhibits a non-equilibrium phase transition of second order resulting in bistability of the steady state. When pushing this reaction system from the near equilibrium side through its critical region to bi-stability, a certain amount of information becomes quasi conserved, thus giving rise to a definition of the degree of order of a self-organizating system. The problem of how the reaction system can be integrated into a greater chemical network as a "bit"-generator, is discussed. To explain what is necessary for the onset of a hard mode instability giving birth to limit-cycle behaviour, a two-component reaction scheme is constructed by superposing onto reaction steps causing conservative concentration oscillations those reactions of the former model system which are responsible for the instability occuring there. By applying the information formalism, again, a quasi-conservation of information is indicated, but with respect to a much smaller time scale. The consequences for using oscillating reaction models as an information pump within a network, and the necessity of a feed-back mechanism in order to get real information storage, are shortly mentioned. Finally, a one-component reaction scheme is outlined that shows successive phase transitions, each of these instabilities bringing out a higher degree of organization.
25Mg2+ Nuclear Magnetic Relaxation in Aqueous Solution
Authors: Holz Manfred , Günther Siegfried , Lutz Otto , Nolle Alfons , Schrade Paul-Gerhard
Published: February 2015

Longitudinal nuclear magnetic relaxation rates of 25Mg2+ have been measured in aqueous solutions of MgCl2 and Mg(NO3)2 as a function of concentration. The value of 1/T1, extrapolated for infinite dilution has been compared with the "electrostatic theory" of Hertz. It turned out that the relaxation rate reflects the high cubic symmetry of the first hydration sphere of 25Mg2+ . Using the 1H and 25Mg2+ relaxation rates at finite salt concentration the "ion-ion contributions" to the 25Mg2+ relaxation rates have been determined. They are compared with those in aqueous LiCl solutions.

A big change in the 25Mg2+ relaxation rate in MgCl2 solution was found when a little amount of sodium citrate was added.
Electrochemical and Specific Heat Measurements on Tellurium-Halogen Systems
Authors: Haag J. , Alpen U. v. , Gmelin E. , Rabenau A.
Published: February 2015

Gibbs free energies of reaction in the systems Te-TeX4 (X = Cl, Br, I) were determined from e.m.f. measurements of solid state galvanic cells using silver halides as auxiliary electrolytes. From the temperature dependence of the e.m.f. the standard entropies and enthalpies of formation S0 (298.15 K) and ⊿Hf
0 (298.15 K) have been calculated for α-TeI, TeI4 , Te2 Br, TeBr4 , Te3Cl2 and TeCl4 . The specific heats of α-Tel and Te2Br were determined from 1.5 K to 300 K by adiabatic and differential scanning calorimetry.
Magnetische Eigenschaften der Normaltemperaturform von CsTmO2 / Magnetic Properties of the Normal-Temperature Form of CsTmO2
Authors: Urland Werner
Published: February 2015

The magnetic behaviour of the normal-temperature-form of CsTmO2 (NT-CsTmO2) has been studied in the temperature range between 2.9 and 251.3 K. In order to interpret the magnetic data a method applying the angular overlap model has been established to assess the crystal-field (CF) parameters of NT-CsTmO2 (CF symmetry: D3d) from the known CF parameters for Tm3+ substituted in YVO4 (CF symmetry: D2d)-With these CF parameters the observed magnetic properties of NT-CsTmO2 can be satisfactorily simulated. The calculation of the paramagnetic principal susceptibilities yields a high magnetic anisotropy, especially at low temperatures. The energy values of the CF levels of the 3H6 ground state are calculated.
The Profile of the Hel 4 3D, 3F – 2 3P (λ = 447.15 nm; λ = 447.0 nm) Spectral Line Emitted from a Low-Pressure Afterglow Plasma Submitted to a Magnetic Field of 10 Tesla
Authors: Drawin H. W. , Ramette J.
Published: February 2015

Measurement of the Hel line at λ = 447.15 nm during the recombination of a helium plasma in a magnetic field of induction B = 10 Tesla by means of a multichannel analyzer system with spectral and temporal resolution showed a Stark-Zeeman broadened line with a superposed line structure. - There are sufficient experimental indications to conclude that this structure is due to molecular transitions, in agreement with the observations for magnetic field-free afterglow plasmas. At the lowest electron densities also some of the weaker Zeeman components of both the allowed and forbidden transitions probably contribute to the structure. The existence of Baranger-Mozer plasma satellites under our experimental conditions could not be confirmed. - We observed further a relatively strong electron density-dependent asymmetry in the intensities of the two main lateral Zeeman-Stark components of the allowed line.
Anisotrope Fluoreszenz langgestreckter Moleküle in Lösungen / The Anisotropie Fluorescence of Prolate Molecules in Solutions
Authors: Kawski A. , Kukielski J. , Kamiński J.
Published: February 2015

Quantum chemical investigations of the electric dipole moments in the ground and excited states and also transition moments of 2,2′-p-phenylenebis (5-phenyloxazole) (POPOP) and 2,2′-p-phenylenebis (4-methvl-5-phenylaxazole) (2MPOPOP) were carried out with the PPP-CI-method. It was established that the transition moments of POPOP and 2MPOPOP are parallel to the long axis, whereas the electric dipole moments are mutually parallel and perpendicular to the long axis of these molecules. Further, the emission anisotropics r of the fluorescence of the prolate molecules POPOP. 2MPOPOP and the non-polar diphenvlenestilbene (DPS) in solvents of different viscosities η were investigated. Also for these substances the non-linear dependence of 1/r on T/η was confirmed. This deviation from the linear dependence is stipulated essentially through the length of the molecule. The effective volumes and the rotational relaxation times in different solvents of the studied molecules were determined.
On a Flexible Double Minimum Potential
Authors: Bohmann J. , Witschel W.
Published: February 2015

The Gauss-perturbed harmonic oscillator, a customary double minimum potential of molecular spectroscopy, is made more flexible by addition of a term α4 · exp(-γ4X4). The matrix elements of the additional term are calculated in the harmonic oscillator basis in terms of parabolic cylinder functions. A sum rule for matrix elements serves as an independent numerical control. The eigenvalues can be given by straightforward diagonalization of the Hamilton-matrix. In addition, upper and lower bounds are given for the partition function.
Homogeneous Photoredox System for Hydrogen Production by Solar Energy
Authors: Gohn M. , Getoff N.
Published: February 2015

In a redox system consisting of 5 × 10-5 mol dm-3 Ru(bpy)32+ complex, 4 × 10-3 mol dm-3 methylviologen and 5 × 10-3 mol dm-3 EDTA in aqueous solutions (pH = 3 to 8.5) without catalyst, hydrogen is formed under illumination with light λ > 360 nm. The highest yield was established in the pH-range between 4 and 5. The degradation of the components by prolonged use was studied spectroscopically. For comparison hydrogen evolution was also studied replacing EDTA by TEA or SCN-, respectively, in the above mentioned system.
Eine vergleichende Untersuchung des Einflusses von 25 Hauptgruppen- und Übergangselementchloriden als externe Spin-Bahn-Kopplungs- Störer auf das Lumineszenzverhalten von Coronen / A comparative Study on the Influence of 25 Main Group and Transition Element Chlorides as External Spin-Orbit Coupling Perturbers on the Luminescence Behaviour of Coronene
Authors: Zander M.
Published: February 2015

A characteristic change in the vibronic structure of the phosphorescence spectrum is the most sensitive external heavy-atom effect observed with coronene. A linear correlation exists between this vibronic effect and the increase of the phosphorescence/fluorescence quantum yield ratio. The observed decrease of the coronene phosphorescence/fluorescence quantum yield ratio in the presence of rare earth chlorides is probably due to an intermolecular energy transfer from the excited coronene molecule to the rare earth ion.
The Conductance of Tetraalkylammonium Iodides in Aqueous Proline and Hydroxyproline Solutions
Authors: Sesta B. , Mesa C. La , Cantale C. , Vincenzini M.
Published: February 2015

The density, viscosity and dielectric constant of aqueous proline and hydroxyproline solutions have been determined at 25 °C. The results appear to indicate that the two aminoacids have a destructive effect on the molecular water aggregates. The equivalent conductance of tetramethylammonium iodide and tetrabutylammonium iodide in aqueous proline and hydroxyproline solutions has been measured at 25°C. The aminoacids increase the viscosity of the solutions and decrease the limiting equivalent conductance of the two electrolytes. Electrostatic interactions of the iodide ions with the water molecules and hydrophobic interactions of the tetraalkylammonium ions with the aminoacids also seem to affect the conductometric behaviour of the electrolytes.
The Pair Correlation Function of the Liquid-Vapour Interface: A Monte Carlo Calculation
Authors: Borštnik B. , Ažman A.
Published: February 2015

A Monte Carlo simulation of the liquid-vapour interface near the triple point is reported. A monotonic density profile is obtained. In the entire interface the pair correlation function g(r) was found to be very close to the liquid bulk g(r), except for the low density region (ϱ(z)/(ϱliq ≦ 0.25 ) where information was inaccessible. The behaviour of the solution of the BGYB equation for the density profile is explored in the context of the new information concerning the pair correlation function in the interface.
Solvent Dependence of the Triplet Reactivity of Pivalophenone as Evidenced by Laser Flash Photolysis
Authors: Naito Ikuo , Schnabel Wolfram
Published: February 2015

Phenyl-t-butylketone (pivalophenone) was irradiated in mixtures of benzene and 2-propanol with 25 ns flashes of 347.1 nm light. Triplet lifetimes were measured by monitoring the decay of the T-T-absorption. 2-propanol exerts a significant stabilizing influence upon the triplet lifetime and lowers the triplet reactivity probably due to a n, π* → π, π* inversion of the lowest triplet state.
The Vibrational Spectra and Normal Coordinate Analysis of 3,3,3-Trifluoropropene and Hexafluoropropene
Authors: Christen D. , Hoffmann V. , Klaeboe P.
Published: February 2015

The infrared spectra of 3,3,3-trifluoropropene and hexafluoropropene were studied in the vapour phase and in solution between 4000 and 40 cm-1 . Raman spectra of the compounds as vapours and liquids were recorded and polarization data obtained.

The spectra of both molecules are interpreted in terms of Cs symmetry. Complete vibrational assignments, including the torsional mode, are presented, based upon infrared and Raman vapour contours, Raman polarization measurements and the results of a normal coordinate analysis
Anisotrope Fluoreszenz von 4-Isocyanat- 4'-dimethylamino-trans-stilben in flüssigen Lösungen / The Anisotropie Fluorescence of 4-isocyanate-4'-dimetkylamino- trans-stilbene in Liquid Solutions
Authors: Kawski A. , Alieka M.
Published: February 2015

In solutions of 4-isoeyanate-4'-dimethylamino-transstilbene (CDS) in benzene, chlorobenzene, cyclohexane and cyclohexanol at 293 K, the fluorescence is strongly anisotropic. The observed emission anisotropics r (polarization degrees P) of CDS in cyclohexane and cyclohexanol are approximately the same and amount t o r = 0.35 ( P = 0.45). This phenomenon is caused by the short lifetime of CDS and processes leading t o a very low quantum yield
Investigation of Mg-Bi Melts by Means of X-Ray- and Neutron Diffraction
Authors: Weber Michael , Steeb Siegfried , Lamparter Peter
Published: February 2015

Neutron diffraction experiments were done on Mg-Bi melts with eight compositions. From the measured intensities total structure factors and pair correlation functions as well as radial atomic distribution functions were calculated. The concentration dependence of the measured nearest neighbour distance and measured coordination number indicates the preference of unlike nearest neighbours within the Mg-Bi melts.

The neutron-intensity curves show premaxima at q ≅ 1.6 Å-1. X-Ray diffraction experiments performed on melts with three different compositions also yield corresponding premaxima. It could be shown that the premaximum intensity from the X-Ray as well as from the neutron experiment corresponds to the assumption that the premaxima are caused by modulation of the monotonic Laue scattering.
Structural Investigation of Bond-Isomeric Hexakis (Thiocyanato-isothiocyanato) osmates (III) from Os LIII-Edge EXAFS
Authors: Rabe P. , Tolkiehn G. , Werner A. , Haensel R.
Published: February 2015

The extended x-ray absorption fine-structure (ENAFS) has been used to determine bond lengths and coordination numbers around the central Os-atom in bond-isomeric hexakis (thiocyanato-isothiocyanato) osmates (III) [Os(NCS)n(SCN)6-n]3-, n = 1,...,6: The above assignment of the species with w-values is confirmed. The Os-N bond length decreases with increasing n while the Os-S bond length is the same in all compounds. The N-bonded ligands form an undistorted linear chain with the central Os-atom. The bond angles between the S-bonded ligands and Os-atoms are distorted by at least 10° around their average value (~ 105°).
Mass Spectrometric Investigations of the Evaporation of Crystalline Compounds of the System Cs2O-Al2O3-SiO2 Part II: The Compounds CsAlSiO4 and CsAlSi5O12
Authors: Odoj R. , Hilpert K.
Published: February 2015

Abstract The evaporation of the synthetic compounds CsAlSiO4 and CsAlSi5O12 was studied by high temperature mass spectrometry. The measurements were carried out under equilibrium conditions with Knudsen cells in the temperature ranges 1242 to 1567 K (CsAlSiO4) and 1542 to 1803 K (CsAlSi5O12). The obtained Cs partial pressures are given by the equations

log p (Pa)=-18497/T(K)+11.85(CsAlSiO4)and

log p (Pa)=-26 974/T(K)+14.6(CsAlSi5012).

The probable uncertainty of the vapor pressures is ± 43%. The following enthalpies of sub­limation of Cs (g) were computed:

⊿Sub H°1405 (CsAlSiO4) =353.6 ± 9.8 kJ mol-1 and

⊿Sub H°1673 (CsAlSi5O12) =516.3 ± 18 kJ mol-1.

The Cs partial pressures over CsAlSiO4, CsAlSi5O12 and CsAlSi2O6 (see part I of this work [1]) are discussed with respect to their consequences for the final storage of high level radioactive waste.
Über die leichten Edelgase in dem Chondriten Kirin / About the Light-weight Noble Gases in the Kirin H-chondrites
Authors: Begemann F. , Braun O. , Weber H. W.
Published: February 2015

Results are reported for the contents of He, Ne, and Ar of three different specimens from the Kirin H-chondrite which, with a recovered weight of about 4000 kg, is the largest known stone meteorite. The concentrations of spallogenic gases cover a range of more than a factor of two; bulk samples with ratios 3He/21Ne ≲ 2 and a FeNi nugget with 3He/38Ar = 8.8 ± 0.6 indicate strong diffusion losses of 3He from the silicates and of tritium from the metal. - Radiogenic 4He and 40Ar have been affected by diffusion, too, resulting in discordant U/Th-4He- and 40K-40Argas retention ages as well as distinctly different ages for different samples. Stepwise heating experiments show the main release of 4He and 40Ar to occur at around 800 °C and the difference in the gas contents to be due to differences in the low-temperature part of the gas release curve. - An attempt is made to account for the observed positive correlation between the concentrations of spallogenic and radiogenic noble gas nuclides. Either the diffusion losses of both have occured at the same time which requires a (quasi-)continuous loss due to a small perihelion distance or a catastrophic event late during the cosmic ray exposure history, but more than about 105 years before the fall of the meteorite. As an alternative model it is suggested that the Kirin meteoroid was hot upon the ejection from its parent body. As the subsequent cooling rate of the meteoroid is smallest in the interior the diffusion losses of radiogenic 4He and 40Ar will be largest where the production rate of the cosmogenic nuclides is smallest.
UV-Absorptionsspektren methylsubstituierter Phenylcyclopropane / UV absorption Spectra of Me thy I substituted Phenylcyclopropanes
Authors: Bhaya Nuhudh D. , Shanshal Muthana
Published: February 2015

The UV absorption spectra of phenyl-cyclopropane(l), 267 nm, 1-methyl-1-phenyl-cyclopro-pane(2), 259 nm, o-tolyl-cyclopropane(3), 264 nm, m-tolyl-cyclopropane (4), 270 nm, and p-tolyl-cyclopropane(5), 280 nm are recorded in the gas phase, in methanol and in n-hexane. The hypsochromic shifts in the spectra of both 2 and 3 are explained in terms of a twisting of the phenylring out of the bisected conformation which causes an increase in the excitation energy. The spectra of 4 and 5, in which no steric factors are expected to twist the phenylring, show typical inductively caused bathochromic shifts. The vibronic structuring of all the absorption spectra are analyzed and found to include the frequencies 984, 964 and 1100 cm-1 that are attributed to the and the νas vibrations of the ν̃s cyclopropyl ring in the excited state. The results of the analysis confirm a recent assumption of a strong participation of the ⊿as Walsh MO of these Molecules in their electronic excitation processes.
Basalts in the Lancé Carbonaceous Chondrite
Authors: Kurat Gero , Kracher Alfred
Published: February 2015

We describe three lithic fragments from the Lancé carbonaceous chondrite which apparently are of igneous origin and of basaltic parentage. They consist of large enstatite grains (pheno-crysts ?) which poikilitically include some olivine and abundant Fe-Ni metal and Fe sulfide blebs. These enstatites are set into a matrix of partly ophitic and partly porphyritic plagioclase (~ an71) and interstitial clinopyroxene and clinopyroxene plus plagioclase intergrowths. Mineral compositions are highly variable and reflect a complex genesis. Olivine compositions range from fo5 to fo60 and sometimes exhibit compositional zoning. Enstatites are mostly of en 98 com-position with some Fe-enrichment towards grain surfaces and cracks. Plagioclases have about an71 but mostly are altered to nonstoichiometric high-alkali compositions (with original Al/Si ratios corresponding to ~ an 70) or are partly replaced by K-free nepheline. Generally two clinopyroxenes are present within the plagiophyric portions of the fragments: One low Fe/Mg augite (~ en53 wo44) rich in Ti, Al, Cr, and Mn (Fe/Mn ≦ 2) and a ferrosalite (~ en15 wo47) poor in Ti, Cr, and Mn (Fe/Mn ~ 100). One fragment also contains spinel (hercynite) which apparently is xenocrystic in nature.

Our investigation indicates: (1) The fragments are of igneous origin. (2) The original melt was of basaltic composition, crystallizing the primary mineral association ol + en + plag + low-Fe augite. (3) During crystallization the melt suffered strong reduction which led to segregation of Fe-Ni droplets from the melt and which continuously lowered the Fe/Mn ratio of successively crystallizing silicates from nearly chondritic (~ 100) to 0.6. (4) Probably after incorporation into the Lancé breccia the fragments suffered to different degrees metasomatic alterations which were caused by the addition of Na, K, and Fe to the system.

The origin of the pre-Lancé basaltic melt cannot yet be established.
The Bulk Composition of the Eucrite Parent Asteroid and its Bearing on Planetary Evolution
Authors: Dreibus Gerlind , Wänke Heinrich
Published: February 2015

It is shown that howardites fit extraordinary well into a binary mixing diagram for both their major and trace element compositions. Eucrites and diogenites would be suitable endmembers. In the mixing diagram computed from the elemental compositions of howardites, we find at a certain position a composition with very special features. This composition designated PR* contains all refractory incompatible elements in almost C 1, i.e. primitive, abundances. If 43% olivine is added to PR* in order to match the C 1 value for the Mg/Si ratio, a composition is obtained which has almost exact C 1 abundance values for all lithophile elements of non-volatile character. Because of its probable genetic relation we have used an olivine composition equal to that of pallasites. An eucrite parent body (EPB) with eucrites, diogenites and pallasites as the major building blocks has been previously suggested by various authors.

The bulk composition of the EPB, resulting from our computations is found to be almost chondritic, but with a considerable depletion of volatile and moderately volatile elements. A comparison of the bulk composition of the EPB with that of Earth and Moon reveals a number of remarkable differences. Thus, the similarity of the composition of the silicate phases of Earth and Moon becomes even more remarkable and must be taken as strong indication for the genetic relationship of Earth and Moon.
Mini-Excitons and Lattice Dynamics in Mixed CT-Crystals: An ESR, Optical and Raman Spectroscopical Study
Authors: Erdle E. , Möhwald H.
Published: February 2015

Mixed CT-crystals of composition anthracenecphenanthrene1-c-tetracyanobenzene (AnthcPhen1-c-TCNB, 0 ≦ c ≦ 1) have been investigated using ESR, optical and Raman spectroscopy. The data yield information on structural features and exciton transport as well as on the interrelation between these properties.

With respect to their structural properties the mixed crystals can be prepared into two classes: orientations and lacking molecular motion as well as a phase transitions. b) Crystals with excess anthracene (c < 0.5) are comparable to Anth-TCNB: they also undergo a first order phase transition though at a lower transitions temperature Tt (Tt = 155 K for c = 0.75, whereas Tt = 206 K for c = 1).

Mini-triplet-excitons confined to the anthracene moiety were found. Their diffusion takes place quasi-onedimensionally and independently of temperature, i.e. especially without being affected by the phase transition. This result holds for the fast component of the diffusion tensor as well as for the slow one.
Irregular Oscillations in a Realistic Abstract Quadratic Mass Action System
Authors: Willamowski K.-D. , Rössler O. E.
Published: February 2015

An open three-variable mass action kinetics is presented which exhibits chaotic behavior under numerical simulation. The elementary reactions of this system are at most of second order and satisfy the requirements of thermodynamics as long as the system is closed.
109Ag NMR-Studies of the Selective Solvation of the Ag+ -Ion in Water-Ethylamine-Mixtures and of the Coordination of Halide-Anions to the Silver-Ethylamine Solvate Complexes
Authors: Kronenbitter J. , Schweizer U. , Schwenk A.
Published: February 2015

109Ag chemical shift measurements of 0.02 up to 3 molar solutions of AgNO3, AgCl, and AgBr in solvent mixtures of H2O (W) and ethylamine (ea) were performed. The extremely long relaxation times T1 and T2 were determined with new techniques.

The Ag+ -ion in solvent mixtures of W and ea shows a strongly selective solvation by ea. The 109Ag chemical shift of the solvate complex [Ag ea2]+ surrounded solely by W is δ2 = (335 ± 2) ppm (referred to the Ag+-ion in W). A further solvation in addition to the inner solvation sphere was determined; this solvation is not or only weakly selective. There is a rapid chemical exchange; the lifetime of the inner solvation sphere is long compared with the Larmor period, whereas the solvation outside this sphere is changed in times shorter than the Larmor period.

In contrast to the NO3- -anion, the halide anions Cl- and Br- are partly coordinated to the [Ag ea2]+ complex. The equilibrium constants for this coordination were determined as well as the chemical shifts of the [Ag ea2 · Cl] and the [Ag ea2 · Br] complexes. The bromine ion is coordinated for shorter times than the Larmor period, whereas the time of the coordination of the chlorine ion may be comparable to the Larmor period or shorter.
Kinetics of the Solid State Reaction between CuO and WO3
Authors: Lazzari M. , Bicelli L. Peraldo , Rivolta B.
Published: February 2015

The solid state reaction of CuWO4-x formation from CuO and WO3 was studied by the contact method in air and nitrogen. The results showed that the reaction is governed by the diffusion of the W6+ and O2- ions and that the rate determining step is the diffusion of oxygen ions in the reaction product. This is in agreement with the defect structure of copper tungstate, an n-type semiconductor with oxygen vacancies through which the diffusion process is possible.
(11̅1,11̅1̅/002) Enhanced Borrmann Effect in Heat Treated Czochralski Grown Silicon Crystals
Authors: Umeno M. , Hildebrandt G.
Published: February 2015

The “enhanced” Borrmann effect present in the ease of simultaneous reflection on (11̅1) and (11̅1̅) (three beam case (11̅1, 11̅1̅/002)) is for the first time applied to the investigation of defects in crystals, i.e. oxygen clusters in heat treated Czochralski grown Silicon. From a comparison of the three beam intensities with those of the two beam case on (220) with CuKα radiation in crystals annealed at 1000 °C it is concluded that at the beginning of the heat treatment a relaxation of the strains due to unstable positioning of the interstitial oxygen atoms and an increase of local strains due to the growth of precipitates proceeded simultaneously.
Prediction of the Influence of Concentration on the Photoluminescence Decay Time of Solutions
Authors: Twardowski R. , Bojarski C.
Published: February 2015

A formula for the donor photoluminescence decay time in its dependence on the concentrations of donor D and acceptor A has been derived from equations for the non-radiative excitation energy transfer between randomly distributed donor and acceptor molecules within a nonactive medium. In the limit [D]/[A] → 0 the formula becomes identical with that of Galanin [7], while in the absence of concentration quenching the fluorescence decay time does not depend on the concentrations.
Solvent Effects on the Spectral Properties of the Methine Dyes
Authors: Salamon Z. , Skibiński A.
Published: February 2015

The spectral characteristics (absorption, fluorescence and lifetimes of fluorescence) of methine dyes in different solvents are presented. The results show that the methine dyes in polar solvents emit a dual fluorescence. From the dependence of the fluorescence spectrum on the dye con-centration it is suggested that excimer formation is responsible for the second band of fluorescence.
Conformation and Structure of Ethylbenzene in the Vapour Phase
Authors: Scharfenberg Peter , Rozsondai Béla , Hargittai István
Published: February 2015

The molecular structure of ethylbenzene has been studied by gas electron diffraction. Experi-mental intensities and radial distribution are well reproduced by an average structure with r = 70(3)°, where r is the angle between the C—C—C(H3) plane and the ring plane, mean (rg) bond lengths (C-C)phenyi = 139.9(3) pm, Cphenyi-C(H2) = 152.4(9) pm, C(H2)-C(H3) = 153.5(12) pm, C—H = 109.4(4) pm, and bond angle C-C-C(HS) = 111.8(15)°. (Estimated total errors are parenthesized.) An also acceptable perpendicular model (r = 90°) is accompanied by very large vibrational amplitudes, while the coplanar conformation (r = 0°) is excluded. Mixtures of conformers fit the experimental data as well. The barrier to rotation of the phenyl group is estimated from the average structure to be about 7 kJ mol -1 . According to CNDO/2 calculations, only the perpendicular form is stable. The results of a geometry optimization are shown.
Vibrational Total Energy Distributions in Terms of Symmetry Coordinates, Forces and Momenta
Authors: Alix Alain J. P. , Rytter Erling
Published: February 2015

The fundamental definitions of the Total Energy and of the Vibrational Total Energy Distributions are presented in details in terms of either symmetry coordinates, or generalised symmetry forces, or generalized symmetry coordinates. This, give now a uniform tool for physicists and chemists in the field of characterisation of the normal vibrational modes of polyatomic molecules.
A Contribution to the Investigation of T2-Relaxation with a Pulse Spectrometer
Authors: Beslmann G. , Dreizler H.
Published: February 2015

We investigated the pressure dependence of the T2- relaxation time for several rotational transitions of acetal-dehyde, CH3CHO. No difference in the relaxation of A- and E-species transitions could be detected. The analysis was performed in the time and frequency domain.
Eine kanonische Transformation als Lösungsvorschlag für eine Funktionalgleichung
Authors: Wahl F.
Published: February 2015

A Canonical Transformation as a Proposal of the Solution of a Functional Equation

Starting with a functional equation of the New Tamm-Dancoff procedure for electronic states of defects in solids we describe an attempt to transform this equation. The aim is to extract a one-particle equation as a projection which is a good approximation for the case of a defect. The transformation usetii s a simple approach to more general canonical transformations leading to inequivalent representations of the many-body problem. It is compared with the elimination procedure given in a first paper [1] which treated the manj-electron problem occuring with the storage of hydrogen in metals
The Incoherent Inelastic Neutron Spectra of TaS2 · NH3 and TaS2(NH3)1/3(H2O)2/3
Authors: Riekel C. , Schöllhorn R. , Tomkinson J.
Published: February 2015

Incoherent, inelastic neutron spectra of TaS2(NH3), TaS2(NH3)1-χ- and TaS2(NH3)1/3(H2O)2/3 were measured in the range 250 cm-1 → 1600 cm-1 . The data suggest the presence of NH4
+ cations and are in agreement with an ionic structure model proposed for these compounds
Experimental Evidence for two Kinds of Defects in Amorphous Fe80B20
Authors: Nold E. , Steeb S. , Lamparter P.
Published: February 2015

The scattering of cold neutrons (λ = 1 nm) with amorphous Fe80
11B20 yields a strong contribution at small q =

(0.07(nm)-1 ≦ q ≦ 2.4(nm)-1) arising from two kinds of defects of different size:

i) Local defects with an extent of about 1.5 nm,

ii) Extended defects with an extent of about 40 to 60 nm, which are interpreted as quasi-dislocations in the amorphous material
Dipole Moment and Dielectric Relaxation of Some Aromatic Ethylenes and Butadienes
Authors: Hanna F. F. , Abdel-Nour K. N. , Risk J. E.
Published: February 2015

The dipole moment of 1,1-bis-p-chlorophenylethylene, 1,1-bis-p-bromophenylethylene, 1,1-bis-pmethoxy, -ethoxy, -isopropoxy-phenyl-ethylene, 1,1,4,4-tetrakis-p-methoxy, -ethoxy, isopropoxyphenylbuta- l,3dienes was measured and compared with the calculated value. The mesomeric moment was estimated and found to decrease in the case of the ethylenes with the increase in volume of the substituted group. For the butadienes, the mesomeric moments compensate each other.

Investigations of the dielectric relaxation times of the ethylenes showed that the orientation of the -OCH3 group in the 1,1-bis-p-methoxy-phenylethylene is hindered to a large extent. The orientation of the -OC2H5 and -OC3H7 groups in the corresponding molecules are restricted due to steric hindrance
Das Photoelektronenspektrum von Pyridin-N-Oxid anhand von Hel/Hell- Intensitäten [1] / Assignment of the Pyridine-N-oxide Photoelectron Spectrum on the Basis of Hel/Hell Intensities [1]
Authors: Klasinc L. , Novak I. , Kluge G. , Scholz M.
Published: February 2015

Comparison of Hel and Hell photoelectron (PE) spectra of pyridine-N-oxide enables the completion of the assignment of its electronic structure
Thermoelectric Power of the Liquid Tin-Lead Eutectic Alloy
Authors: Kurlat D. H. , Zadunaisky de Bäsch D. , Rosen M.
Published: February 2015

We have measured the Seebeck coefficient of the Sn0.74- Pb0.26 liquid alloy, in the temperature range 190° C- 700° C. The results were compared with those predicted by the Faber-Ziman theory
Hollow Cathode Discharges for Gas Lasers
Authors: Rózsa Károly
Published: February 2015

A review of hollow cathode discharges for gas (metal vapour) lasers is given. Particular attention is paid to the arc free discharge region and to the possibility of increasing the intensity of the ionic spectrum of the discharges
Exciton Phosphorescence of p-Terphenyl Crystal at 300 K
Authors: Morikawa Eizi , Kotani Masahiro
Published: February 2015

Exciton phosphorescence from pure p-terphenyl crystals was observed at 300 K. The 0-0 band of the phosphorescence spectrum was found at 20.4 X 103 cm-1 . The vibrational progression of 1.46 x 103 cm-1 is present. The maximum exciton lifetime observed was 200 ms. The excitation spectrum of the exciton phosphorescence differs considerably from that observed in glassy solution, but is poorly structured as well. The absorption coefficient near the origin is small. The absence of sensitized delayed fluorescence from doped tetracene suggests that the triplet energy transfer to this guest is not diffusion limited.
EPR Study of the Nematic Liquid Crystals: PEBAB and EBRA
Authors: Rao A. S. N. , Murty P. Narayana , Murty C. R. K. , Reddy T. Rs.
Published: February 2015

By EPR two nematic liquid crystals PEBAB and EBBA were investigated. The experimental variation of the order parameter with temperature is corroborated with theory. In EBBA a spectrum reminiscent of glassy nature is observed at - 60° C.
Photoelectron Spectroscopy of Heterocycles 1-(Diazinyl)-2-(Pyridyl)-ethenes (Triazastilbenes)
Authors: Novak I. , Klasinc L. , Knop J. V. , Bluhm Th.
Published: February 2015

The photoelectron (PE) spectra of 1-(4-pyrimidyl)-2-(3-pyridyl)-ethene 1, 1-(2-pyrimidyl)-2- (3-pyridyl)-ethene 2, 1-(4-pyridazinyl)-2-(3-pyridyl)-ethene 3, 1-(3-pyridazinyl)-2-(3-pyridyl)- ethene 4 and 1-(2-pyrazinyl)-2-(3-pyridyl)-ethene 5 all in their trans conformations have been recorded using Hel radiation. Comparisons with the PE spectra of styrylpyridines, dipyridylethenes and diazabenzenes allowed the assignment of all ionization energies, Ei, corresponding to π- and nitrogen lone pair ionizations in the region of Ei < 12 eV. The variations in PE spectra of five isomeric triazastilbenes studied are due to different nitrogen atom positions in the diazinyl ring.
Repulsion Phenomena in Thin Layers of Alcoholic Solutions of Tetrabutylammonium Iodide
Authors: Peschel G. , Belouschek P.
Published: February 2015

The structural disjoining pressure of methyl-, ethyl-, n-propyl, and n-butyl alcohol was deter-mined in thin layers between highly smooth rutile surfaces when tetrabutylammonium iodide was added. The a verage thickness of the oriented solvation layers per interface turned out to be largest for methyl alcohol (about 1.5 nm) and decreases like the disjoining pressure when passing to the related alcohols with longer chain lengths. Tetrabutylammonium iodide clearly reduces the thickness of the boundary layer with increasing concentration.
Limitations on Mass Separation by the Weakly Ionized Plasma Centrifuge
Authors: Wijnakker M. M. B. , Granneman E. H. A.
Published: February 2015

bstract

A In weakly ionized argon and xenon rotating plasmas the rotational velocity and the temperature and pressure distribution have been measured.

The stationary discharge is generated by two opposed cathode-anode configurations. The arc current of 100 A is drawn across an axial magnetic field up to 0.26 T. The filling pressure ijs varied between 1 and 10 torr.

The rotational velocity is found to be proportional to the discharge current and the magnetic field and inversely proportional to the viscosity of the neutral gas. The rotational kinetic energies of the particles in the argon and xenon discharge are about equal. Because the temperature of the argon discharge is lower than that of the xenon discharge, the pressure rise in radial direction due to centrifugal forces is steeper for the former.

A theoretical analysis taking into account viscous dissipation as the only heating mechanism yields a heavy particle temperature T which imposes an upper limit to the ratio X =½m υθ
2/kT of order unity. The maximum attainable separation factor α is therefore limited in these types of centrifuges. Experimentally, in the parameter region studied, X is found not to exceed a value 0.4 in argon discharges and 0.2 in xenon discharges. A rough estimate shows that besides viscous dissipation other heating mechanisms are also important. Ohmic heating, for instance, is at least a factor 6 larger than the viscous dissipation.
Über einige präparative Probleme zum Hexachlorotechnetat und ihren Einfluß auf die Messung der Zerfallskonstanten des 99mTc in Hexahalogenokomplexen / About some preparative problems concerning hexachlorotechnetate and their influence on the measuring of the decay constant of 99mTc in hexahalogeno complexes.
Authors: Dostal K.-P. , Bayerl B.
Published: February 2015

A discrepancy between theoretical and experimental values concerning the variation of decay constant of 99m Tc is cleared up. A new preparation of hexachlorotechnetate complex by reduction of pertechnetate ion with hydrazine is given. The corrected experimental results are

λ(TcO4-) -λ(TcCl6--) = (1,93 ± 0,12) · 10-3 1λ,

λ(TcO4-) -λ(TcBr6--) = (2,44 ± 0,30) · 10-3 λ,

λ(TcO4-) -λ(TcJ6--) = (3,22 ± 0,29) · 10-3 λ.
Die Viskositätsabhängigkeit der Fluoreszenz - Anisotropie und der Lebensdauer von Trans-Stilben / Influence of Viscosity upon the Anisotropic Fluorescence and Lifetime of trans-Stilbene
Authors: Alicka M. , Bauer R. K. , Kawski A.
Published: February 2015

The fluorescence anisotropy r and lifetime τF of trans-stilbene in different solvents has been measured and the dielectric relaxation time from Perrin and Debye equations has been determined. The fluorescence lifetime in the viscosity region from 0.321 to 61.92 Nm-2s, varies between 30 and 152 ps.
Investigation of Molecular Motion in Smectic Phases of the Liquid Crystal TBBA by NMR Relaxation Dispersion
Authors: Mugele Th. , Graf V. , Wülfel W.
Published: February 2015

The proton spin T1 relaxation dispersion in the smectic A and C phase of TBBA, and for comparison also in the nematic phase, have been studied using time dependent fast field-cycling techniques in the Larmor frequency range from νp = 100 Hz to 44 MHz. Our measurements considerably extend recent ones by Blinc et al., performed with other NMR methods for frequencies ≧ 140 kHz. The new experimental data are consistent with the reported ones for Sm C but not for Sm A, the difference being that the essential T1 dispersion observed with our technique occurs at much lower frequencies, namely below about 100 kHz. As a consequence, the relaxation dispersion for both smectic phases looks very similar. It can be described quantitatively in terms of relaxation by "nematic-like" order fluctuations, self-diffusion, and by a third molecular mechanism with (for simplicity) Debve-like power spectrum, which is possibly a second type of order fluctuation or a molecular rotation about the short axis. The analysis reveals surprisingly far going parallels between the spin relaxation of simple smectics and that of high-temperature nematics like PAA.
The Influence of the Grain Shape on X-Ray Line Broadening
Authors: Schattschneider P. , Wagendristel A.
Published: February 2015

The analysis of X-ray reflections allows for the determination of the grain dimension in the direction of the bisector of the incident and scattered radiation. It is shown that correct results will be obtained only as long as the grain dimensions perpendicular to this direction are sufficiently large. The possible errors are estimated. The conditions for the determination of the shape anisotropy are discussed.
Semiempirical Studies of Inner-Core Energy Levels. IV. ESCA Shifts of Nitrogen Atoms in Different Chemical Environments by the SCC-MO Method
Authors: Maksić Z. B. , Rupnik K.
Published: February 2015

The binding energy shifts of the Is levels of nitrogen atoms in 15 different bonding situations are calculated by the self-consistent charge molecular orbital (SCC-MO) method employing an electrostatic potential model in the point charge approximation. The standard deviation of the obtained correlation is ~ 0.5 eV, which is substantially better than the earlier CNDO/2 GPM and RPM results. The scatter of the correlated values is diminished to roughly 1/3 of the previous CNDO/2 results. The merits and shortcommings of the electrostatic potential model are briefly discussed. It is concluded that the present approach provides a useful tool for studying ESCA shifts in large molecules of biochemical interest.
Effect of Acceptor Concentration upon Donor Fluorescence Decay and Quantum Yield
Authors: Bojarski C. , Grabowska E.
Published: February 2015

The fluorescence decay times (τ/τ0) and quantum yields (η/η0) of rhodamine 6G (donor) in their dependence on the concentration of malachite green (acceptor) in ethanol were measured for the donor to acceptor concentration ratios γᴅ/γᴀ 3.48 and 0.35. At fixed γᴀ, the values of τ/τ0 and η/η0 are markedly lower for the systems with higher γᴅ/γᴀ. The experimental results are compared with the theory of a multistep excitation energy transfer from donor to acceptor. Good agreement between theory and experiment was found for the critical distances ROD = 60.7 Å and ROA = 53.8 Å calculated from spectroscopic data. In the case of γᴅ/γᴀ = 0.35, the experimental results can also be properly described using the Förster-Galanin theory, whereas for the system with γᴅ/γᴀ - 3.48 the multistep energy transfer plays a significant role.
Functional Quantum Theory of the Nonlinear Spinor Field as a Lepton-Hadron Model with Quark-Confinement
Authors: Stumpf H.
Published: February 2015

The non-canonical Heisenberg dipole regularization of a nonlinear spinor field is interpreted as a system of lepton quark pairs in the one-particle sector. In the frame-work of functional quantum theory a method is given to derive an independent lepton-quark dynamics with quark confinement from the fundamental spinor field.
Kraftkonstanten des VO4
3- -Ions im Zirkon-Gitter [1] / Force Constants of the VO4
3- Ion in the Zircon Lattice
Authors: Escobar Marta E. , Baran Enrique J.
Published: February 2015

Force Constants of the VO4
3- Ion in the different rare earth orthovanadates of the zircon type have been computed using a modified valence force field and recently reported Raman data. It is shown that the V-O bond strenghtening runs parallel to the unit cell contraction. The Raman spectrum of the tetragonal modification of LaVO4 is reported for the first time.
Diffusion in Binary Nonelectrolyte Solutions
Authors: Haase R. , Jansen H.-J.
Published: February 2015

For binary liquid mixtures of nonelectrolytes, we consider the dependence of the diffusion coefficient on composition and temperature, making use of an analytical expression for the kinematic diffusion coefficient (diffusion coefficient divided by thermodynamic factor). We present recent experimental data for the ideal liquid system chlorobenzene + bromobenzene and for the non-ideal liquid system water -f methanol as well as literature data for other non-ideal mixtures.
Determination of a High Potential Barrier Hindering Internal Rotation from the Analysis of the Ground State Spectrum: The Case of Ethyl Cyanide
Authors: Boucher D. , Dubrulle A. , Demaison J. , Dreizler H.
Published: February 2015

The ground state rotational spectrum of ethyl cyanide has been reinvestigated between 8 and 250 GHz. The barrier potential V3 is calculated from 11 high J, ground state transitions which were found split into doublets. V3 is 3007 cal/mole, assuming Iα = 3.167 u Å2 and ∢ (i,a) = 48.65°. The splittings of the K-doublet transitious have also been analyzed.
Non-Equilibrium Relaxing Gas Flow Behind Three Dimensional Unsteady Curved Shock Wave
Authors: Sharma V. D. , Shyam Radhe
Published: February 2015

A shock wave is assumed to exist in a three-dimensional unsteady flow of a relaxing gas. The variation of flow parameters at any point behind the shock surface is determined in terms of the shock geometry and the upstream flow conditions. The expressions for the vorticity and the curvature of a streak line at the rear of the shock surface are also determined in terms of the known quantities.