bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zur Bildung und Umwandlung der „blauen“ und „grünen“ Zentren im goldaktivierten Zinksulfid / On the Formation and Conversion of “Blue” and “Green” Centres in Gold-Activated Zinc Sulphide
Authors: Kynev K. , Kuk V. 
Published: February 2015

Abstract
The phosphor ZnS-Au activated in the presence of zinc exhibits a blue emission band (Emax = 2,58 eV) which can be ascribed to associated Au′Zn-Vׄs-centres. A reversible interconversion of “blue” and “green” centres is achieved by retiring the phosphor samples in a suitable gas atmosphere
Lattice Vibrations and Ideal Electrical Resistivity of Noble Metals
Authors: Singh B. P. , Hemkar M. P. 
Published: February 2015

Abstract
The phonon dispersion in the three principal symmetry directions [ζ00], [ζζ0] and [ζζζ] and the temperature variation of the electrical resistivity of Cu, Ag and Au have been studied by using a lattice dynamical model which takes into account d shell-d shell central interactions up to second neighbours. The calculated results have been compared with the available experimental data and have been found to be in a satisfactory agreement.
Polarization, Barriers and Tunneling Times of Some Tautomers of Adenine and Thymine
Authors: Marañon Julio , Sorarrain Oscar M. 
Published: February 2015

Abstract
The polarization of the radiation involved in some transitions is analysed for the normal and tautomeric forms of adenine and thymine. Tunneling times for some barriers previously reported [1] and equilibrium constants between two isomers for some excited states are also given. The calculations have been made with the CNDO/2-CI method and the results compared with the available experimental data.
Networks Induced in Nonlinear Chemical Reaction System by Symmetries of Transformation Groups
Authors: Busse H. G. , Havsteen B. H. 
Published: February 2015

Abstract
Physical systems possess a structure and display dynamics. The article describes how a structure of one class of systems, which are encountered in chemical kinetics, can be revealed. The structure may be represented by a graph that has some similarities with the graph used to dis-play the structure of chemical molecules. The graphs are induced by one-parameter trans-formation groups in nonlinear systems. The model system of Dreitlein and Smoes is treated as an example.
Notizen: Mechanism of CaMoO4 Formation in the Solid State from CaO and MoO3
Authors: Flor G. , Berbenni V. , Massarotti V. , Riccardi R. , Tkacenko E. V. 
Published: February 2015

Abstract
The formation in the solid state of CaMoO4 from CaO (single crystal) and MoO3 was investigated by the contact method in the temperature range 625-710 °C and at 10−4 < po2 < 1 atm.
The relatively high velocity of this process compared with that for CaWO4 formation is explained on the basis of the different types of lattice disorder predominant in the two reaction products.
As concerns CaMoO4, the majority defect pair (VMo
6′, h·) was deduced by Wagner and Schmalzried's method.
The overall results indicate that the rate-determining step of CaMoO4 formation is the molybdenum diffusion via VMo
6′ .
Luminescent Heterocycles. IX pH Dependent Fluorescence Spectra of Chromone, 2-Methylchromone and 7-Hydroxy-2-Methylchromone [1]
Authors: Wolfbeis Otto S. , Knierzinger Andreas 
Published: February 2015

The fluorescence spectra of the title compounds have been measured in the pH 9 to H0 -9 acidity range at 25 °C. Chromone and its 2-methyl derivative fluoresce intensely from their protonated form, whereas the uncharged molecules are nonfluorescent. Förster cycle calculations show chromone to be more basic in its first excited singlet state than in its ground state, but protonation proceeds incompletely during the lifetime of the excited molecule.
7-Hydroxy-2-methylchromone (7-HMC) fluoresces in water, depending upon the solvent acidity, from its anion and a zwitter-ion (or phototautomer or exciplex), but not from the neutral molecule. pKa, values are given for both the ground and excited state and drastic differences are found: The 7-HMC anion in its S1-state is first protonated at the carbonyl oxygen rather than at the phenolate oxygen.
Attention is drawn to the extrem solvent and acidity sensitivity of the fluorescence maxima and intensities of 7-hydroxy-chromones with respect to possible analytical determinations of naturally occurring derivatives using luminescence spectroscopy
The Influence of Molecular Transitions on the Spectrum of the Helium Line at λ= 447.15 nm in a Low-Pressure Discharge
Authors: Pinnekamp F. 
Published: February 2015

Abstract
In a linear pulsed discharge of helium the spectrum of the atomic transition 43D, F→23P at → - 447.15 nm is measured time resolved by a multichannel analyzer. Pronounced structures of the line profile, reported by other authors could not be verified and helium molecular lines did not occur in the parameter range of this discharge below 100 Pa. The measured influence of spurious hydrogen might suggest the interpretation of the recently observed structures as being due to hydrogen molecular transitions.
Chemisorption on a FCC Metal Surface: Electronic Structure of Ordered Overlayers
Authors: Masuda Kin-ichi 
Published: February 2015

Abstract
A Green's function perturbation technique is presented which is appropriate for studying the chemisorption behavior of ordered atomic layers on a metal surface. The phase shift technique is used to determine the change in the electronic density of states due to chemisorption. The method is quite general and can be used to study the electronic structure of arbitrary ordered overlayers. Numerical results are given for p(2x2), c(4x2), p(2x1), c(2x2) and p(1X1) overlayers on a (001) surface of a tight-binding fee metal. It is shown that the effects of long-range order and the binding geometry of the adsorbate layer are of great importance for the electronic structure of ordered overlayers.
Investigation of Methyl Reorientations in 1,4-Dimethoxy- 2,6-dimethylbenzene by NMR and Inelastic Neutron Scattering
Authors: Wind R. A. , Bovée W. M. M. J. , Kupers J. C. F. , Smidt J. , Steenbergen Chr. 
Published: February 2015

Abstract
In this paper a solid state NMR relaxation study and inelastic neutron scattering (INS) experiments (the latter in the solid and liquid phase) are reported for a molecule containing methyl groups in different surroundings, namely 1,4-dimethoxy-2,6-dimethylbenzene. The results are compared with each other and with those of a liquid state NMR study reported earlier. It is found that in this way both the shapes and magnitudes of the various hindering potentials can be determined.
The result is that the methyl groups 1, 2 and 4 possess a threefold cosine-shaped potential with heights given by 7.7, 9.0 and 15.0 kJ/mol according to the solid state NMR measurements (from the INS study the values 7.5, 7.5 and 16.0 kJ/mol were obtained). For methyl group 6 a mixture of a three-and six-fold symmetry had to be taken into account in order to explain the experiments. Except for methyl group 4 the liquid state NMR results deviate from those obtained with the other two techniques. A possible cause for this discrepancy is discussed.
For the molecular structure it is concluded that the reorientations of the methyl groups 1 and 2 are influenced by mutual hindering and that the angle between the plane through the C4-O-C bond and the aromatic plane is small, whereas for the C1-O-C bond this angle is estimated to be about 70°.
LEED Intensity Measurement by Photographic Method with Digital Image Processing
Authors: Ueda K. , Lehmpfuhl G. , Reuber E. 
Published: February 2015

Abstract
An accurate photographic method for measuring intensities on a fluorescent screen is described. Simultaneously with the fluorescent screen a calibrated 7-step grey scale is recorded on the film. Using a scanning photometer the intensity distribution can be digitized and by comparison with the grey scale converted to electron current density. As an example LEED-intensities from a Si (lll)-surface obtained with the photographic technique are compared with spot-photometer measurements.
Monte-Carlo-Simulation des Abklingverhaltens von Kristallen am Beispiel des Anthracens / Monte-Carlo-simulation of the fluorescence decay of anthracene single crystals
Authors: Ganz P. , Ganz S. 
Published: February 2015

Abstract
Computer Simulation of the fluorescence decay of an anthracene single crystal shows that strong reabsorption leads to nonexponential decay curves.
Kinetic Parameters from Thermogravimetric Data
Authors: Marini Amedeo , Berbenni Vittorio , Flor Giorgio 
Published: February 2015

Abstract
The "differential" method of Achar, Brindley and Sharp (ABS) and the "integral" one of Coats and Redfern (CR) are applied to the dehydration of BaBr2-H20 and HCOOLi-H20 and to the thermal decomposition of Pb(SCN)2, and the kinetic parameters so obtained are compared with those deduced isothermally. The results of the ABS method, at the lowest heating rate (q = 1.2 K min — '), agree well with the isothermal ones, whereas the CR method leads to satisfactory results only for the Pb(SCN)2 thermal decomposition (q = 1.2 K min~*). A possible explanation is given.
A Study of a Weakly Ionized Rotating Plasma
Authors: Wijnakker M. M. B. , Granneman E. H. A. , Kistemaker J. 
Published: February 2015

Abstract
Measurements are reported on a weakly ionized rotating argon plasma generated by two identical gas discharges facing each other. In each discharge a current up to 100 A is drawn between a point-like cathode and a ring-shaped anode. Axial magnetic fields up to 0.26 T are applied. All measurements have been done at 1 torr.
For magnetic field strengths below 0.17 T the plasma has a more or less uniform radial distribution; above 0.17 T a contracted plasma column is present along the axis of the cylinder.
In the symmetry plane between the two discharges measurements have been done on the rotational velocity of neutrals and ions, the electron density and temperature, the ion temperature, the plasma potential and the radial pressure distribution. The rotational velocity, the plasma potential and the pressure distribution are also calculated. The theoretical treatment is based on the theory developed by Klüber and Wilhelm and Hong.
In the low magnetic field case velocities of 700 m/sec are found for ions as well as neutrals. The agreement between theory and experiment is good in this case. At high magnetic fields, the ions and neutrals are found to have azimuthal velocities of 1900 and 700 m/sec, respectively.
The radial pressure enhancement due to the centrifugal forces is found to be approximately a factor of two whereas the theory predicts only a factor of 1.2.
In a discharge in which a mixture of argon and xenon is used a relative separation factor of 2.15 is found.
Adiabatic Potentials of the Alkali-Rare Gas Atom Pairs
Authors: Czuchaj E. , Sienkiewicz J. 
Published: February 2015

Abstract
The semiempirical potential-model calculations of Baylis have been repeated with some modifications. Firstly, an exact calculation of the Pauli exclusion pseudopotential for the repulsion between alkali core and rare gas atom has been carried out. Secondly, the new atomic radial orbitals proposed by Simons were taken for the calculation instead of those of the Bates-Dam-gaard type. The adiabatic potentials calculated here have, in general, a similar character as the previous ones obtained by Pascale et al. However, many of them are seriously modified.
Thermal Motion of Prolate Luminescent Molecules in Solvents with Different Viscosities
Authors: Kawski A. , Kamiński J. , Kukielski J. 
Published: February 2015

Abstract
The emission anisotropies r of the fluorescence of the prolate molecules 4-dimethylamino-4′-nitrostilbene (DNS) and 4-amino-4′-nitrostilbene (ANS) in solvents of different viscosities η were investigated. The non-linear dependence of 1/r on T/η was confirmed. Agreement between the experimental data and theory was obtained by the assumption that the prolate luminescent molecules perform irregular rotational motions within a limited solid angle. The theory developed for prolate molecules with the emission transition moment parallel to the long axis of the molecules describes well the experimental results. Rotational relaxation times in different solvents and effective volumes of the studied molecules were obtained.
Lattice Dynamics and Thermal Expansion of Ruthenium
Authors: Rao R. Ramji , Murthy J. V. S. S. Narayana 
Published: February 2015

Abstract
The lattice dynamics, lattice specific heat and thermal expansion of ruthenium are worked out using the model of Srinivasan and Ramji Rao, based on Keating’s approach. A total number of 50,880 frequencies has been used in constructing the frequency distribution function. The anharmonic parameters are obtained from the data of Clendenen and Drickamer on the pressure variation of the lattice parameters of ruthenium. The Anderson-Grüneisen parameter δ is calculated using the theoretical TOE constants, and the temperature variation of the bulk modulus is explained using Anderson’s theory.
Notizen: A Contribution to the Stark-Spectroscopy at Low Microwave Frequencies
Authors: Schrepp W. , Dreizler H. 
Published: February 2015

Recently we published a construction of a micro­wave-microwave double resonance spectrometer [1], which allows a variety of experiments. An essential part of it is a “stripline” absorption cell.
Although Stark-Spectroscopy [2] gave a very important impetus to the investigation of rotation spectra and is in use for three decades, measure­ments below 6.5 GHz are few in number compared to the frequency region above 6.5 GHz.
The reason is that generally the line intensity decreases at lower frequencies and the cross sections of the standard waveguides are larger. If one does not use special waveguides * a higher Stark voltage has to be applied to produce the necessary Stark field for modulation. This requires a rather powerful Stark square wave generator** to load and unload the capacity of the absorption cell.
Measurements in the low frequency region may be useful since at these lower frequencies the density of rotational spectra is sometimes considerably lower than at higher frequencies, which faciliates the assignement.
We noticed that the stripline cell, which transmits from DC to 18 GHz in a coaxial type mode, may be used for Stark-Spektroscopy by feeding the Stark voltage and the microwave simultaneously to the septum. After having finished our experiments, we noticed that S. Weisbaum [4] et al. measured the transitions 32 - 3a and 52 - 53 of HDO at 486.50 and 824.64 MHz, respectively, by a similar tech­nique. The radiofrequency was connected together with the Stark voltage to the septum of a conven­tional Stark cell.
In Fig. 1 we give the details of the set up. To combine the microwave and the square wave we use “monitor tees” *. The square wave is fed into the monitor port which transmits a 100 kHz square wave. For example, a residual square wave of 140 V is observed at the microwave port when applying a 400 V square wave. To prevent any influence of the square wave on the microwave sourcje we use a piece of waveguide as a high pass filter. At the output of the absorption cell another piece af waveguide acting as a high pass filter protects the detector cristal. The cell we used for the measurements presented in Table 1 and Fig. 2 is made of an X-band waveguide R100 (cut off for the TE10-mode 6.56GHz). The construction is similar to that given in Fig. 1 of the previous paper [1], but TNC connectors** are used. The cell has been tested for a voltage of 2500 V between septum and the waveguide walls. The attenuation of the microwave on the stripline between 0.4 and 2.4 GHz is about 1.5 dB.
On Centrifugal Distortion and Urey-Bradley Force Field of Chlorofluoromethane
Authors: Jaman A. I. , Nandi R. N. 
Published: February 2015

Abstract
A normal coordinate treatment of chlorofluoromethane has been performed in the Urey-Bradley force field model using the centrifugal distortion constants and the vibrational frequencies. Since the molecule has only one plane of symmetry (Cs), the symmetrized internal coordinates have not been used in the calculation. The effect of the angular redundancy has been rigorously treated and the derived force constants are in good agreement with those of other halogenated methane.
NMR Pulsed Field Gradient Study of Self-Diffusion in the Isotropic Phase of the Liquid Crystals MBBA and EBBA
Authors: Rollmann G. , Reinhart K. F. , Noack F. 
Published: February 2015

Abstract
In refinement of a previous study made by Hayward and Packer, the self-diffusion coefficients D of the nematogen liquid crystals MBBA and EBBA were remeasured in the isotropic phase by means of the NMR pulsed field gradient technique. In particular, the diffusion measurements were made for the first time at different Larmor frequencies. A comparison with results obtained recently on the same samples by NMR T1 relaxation analysis reveals a severe discrepancy. Since the gradient method gives results in essential agreement with optical spectroscopies, the observed discrepancy must be attributed to shortages of the relaxation analysis (incorrect models, insufficient experimental accuracy). It is also shown that D depends more strongly on the molecular weight m than m-1/2 .
Synthesis and Properties of a New Kind of One-Dimensional Conductors. 2. Extended Hückel Calculations on the Energy Band Structure
Authors: Seelig Friedrich Franz 
Published: February 2015

Abstract
The co-ordination polymer of tetrazaporphin (TAP) with a transition metal, say FeII , in its center and acetylide anion, C2
2⊖ , as an axial bidentate bridging ligand is taken as a model sub-stance for the new type of one-dimensional conductors introduced in the preceding communication of this series. Although the monomer shows D4h symmetry, this is reduced to C4v for arbitrary kz -values of the Bloch functions of the first Brillouin zone. From the irreducible representations a1, a2, b1, b2, and e only a1 and e have contributions from all components, namely TAP2⊖ , Fe2⊕ and C2
2⊖, so that for these races broad energy bands can be expected. The a2, b1, and b2 MOs of the TAP-FeII subunits are separated fairly well and have no counterparts in the C2
2⊖ bridges so that very narrow bands should arise. This is confirmed by an EH calculation. Unexpectedly the a1 bonds which have contributions from the σ-MOS of C2
2⊖ are broader than the e-bands which contain the two crossed π-MO systems of C2
2⊖ . The quantitative results of the nearly self-consistent iterative EH calculation indicate overlap of the energy bands near the Fermi level and fulfill thus one necessary condition for metal-like electrical conductivity.
An Investigation of the Positive Column of a Hollow Cathode Arc in a Magnetic Field. Part II
Authors: Janssen P. A. E. M. , Boeschoten F. 
Published: February 2015

Abstract
It is shown that the behaviour of the highly ionized and magnetized plasma in the positive column of the hollow cathode arc (described in Part I of this investigation) may be well explained with the macroscopic equations on basis of the MHD ordering (eEr ⪢ ⊿p/ne). In particular the rotation of the plasma column around its axis is properly described by an equation for the electrical potential.
Viscous effects (due to ion-ion collisions) play an important role in the transport of particles, momentum and energy. The strong shear in the plasma rotation goes along with an inwardly directed ion flux, oppositely to the "classical" outward ion flux (due to ion-electron collisions), thus leading to an improved confinement of the ions. As the electron viscosity is negligible, the electrons move outward with the "classical" velocity. The resulting non-ambipolar plasma transport leads to an inwardly directed current and the corresponding j X B force drives the plasma rotation against the friction of the ions (ion-ion and ion-neutral collisions).
The stationary power balance is well fulfilled by the ions, and within a factor two also by the electrons. Most of the power is handled by the electrons.
Energielücke bei Polymethinstreptocyaninen unendlicher Kettenlänge / The Energy Gap in Polymethinestreptocyanines of Infinite Chain Lengths
Authors: Tyutyulkov N. , Fabian J. , Polansky . E. 
Published: February 2015

Abstract
Extrapolation of the experimentally determined energies of the longest wavelength transition in the polymethinestreptocyanine series yields a value of 1.0 eV for the energy gap.
Dispersion der gekoppelten Wellen beim stimulierten Raman-Effekt unter Berücksichtigung der dielektrischen Dispersion / Dispersion of Coupled Waves of Stimulated Raman-Effect with Regard to Dielectric Dispersion
Authors: Merten L. , Wenk J. 
Published: February 2015

Abstract
It is shown that the dispersion functions of coupled waves depend very sensitively on the dielectric dispersion in the visible frequency region. The dispersion functions of all six coupled waves can be described by explicit formulae in very good approximation.
Experimental Profiles of the Balmer Line Hβ Emitted from an Afterglow Plasma Without and With a Superposed Magnetic Field up to 10 Tesla
Authors: Drawin H. W. , Ramette J. 
Published: February 2015

Abstract
The profile of the Hβ line emitted from an afterglow plasma in pure hydrogen gas and a mixture of hydrogen and helium has been measured in axial direction using a multichannel spectrum analyzer with additional temporal resolution. Measurements were performed without and with a superposed magnetic field (B ≦ 10.8 Tesla) in axial direction. With magnetic field we observed a rather strong dependence of the wavelength positions of the two lateral "Zeeman components" (intensity maximum due to combined Stark-Zeeman effects). This feature is important in radiative transfer calculations and for the spectroscopic determination of magnetic fields in plasmas. - Both with and without magnetic field we always observed a line structure superposed on the Hβ profile. The structure disappeared in an active electrical discharge and changed with gas composition. The line structure is interpreted as being due to electronic transitions of molecular hydrogen. It is very probable that the "satellite structures" of Balmer lines observed by other authors under quite different experimental conditions and interpreted as dynamical Stark effect splitting due to fluctuating electric fields have in most cases the same molecular origin. Our earlier published line profiles of Hβ for B = 0 [J. Ramette and H. W. Drawin, Z. Naturforsch. 31 a, 401 (1976) ] are revised in the present paper.
Radiation Pressure Dominated Plasma Flow
Authors: Mulser P. , Spindler G. 
Published: February 2015

Abstract
The influence of light pressure on plane and spherical plasma flows is treated. Numerical calculations show that smooth laser pulses lead to formation of an overdense plateau if thermal transport is non-negligible there, and that an originally supersonic flow becomes subsonic in this region. The results are consistent with analytical considerations. Density humps, as reported in the literature, are found in conjunction with spiking pulses or prepulses only.
Resolution of K-Splitting in the Rotation-Inversion Raman Spectrum of Ammonia NH3
Authors: Cloppenburg B. , Manczak K. , Prockl H. , Schrötter H. W. , Strey G. 
Published: February 2015

Abstract
The rotation-inversion Raman spectrum of the NH3 molecule has been photoelectrically recorded. The K-splitting in the R-and S-branch could be partly resolved. The intensity contour has been simulated by use of a computer program.
Mikrowellen-Spektrum und rotationsspektroskopische Konstanten des 1,3-Dichlorpropins [CH2ClC≡CCl]
Authors: Günther H. , Zeil W. 
Published: February 2015

Abstract
The microwave spectra of three isotopic species of CH2ClC≡CCl were investigated and assigned. We report the rotational constants, centrifugal distortion constants and the nuclear quadrupole coupling constants.