bluuebunny/crossref_metadata_2025_split huggingface dataset:
Adsorption, Desorption, Dissoziation und Rekombination von SO2 an einer Palladium(111)‐Oberfläche
Authors: Kölzer J. G. , Wassmuth H.‐W. 
Published: May 2007

AbstractDie Adsorption, Desorption sowie Zerfalls‐ uud Aufbaureaktionen von SO2 an Pd(1 1 1) wurden mit LEED, AES, Thermischer Desorptions‐Massenspektrometrie und Molekularstrahlstreuung im Temperaturbereich 160‐1200 K untersucht. Bei 160 K adsorbiert SO2 molekular und ungeordnet; die Precursor‐gesteuerte Adsorption mit einem Anfangshaftkoeffizienten s0 = 1 führt bei Sättigung zu einem Bedeckungsgrad Θ ≈ 0,3. Beim Hochheizen der Adschicht desorbiert ausschließlich SO2, und zwar im α‐Peak (Tmax = 240 K) direkt aus dem Zustand (SO2)ad und im β‐Peak (Tmax = 330‐370 K) als Produkt der Rekombination von (SO)ad und Oad. Ein großer Teil des bei der SO2‐Dissoziation freiwerdenden Sauerstoffs wird in den „Subsurface”︁‐Bereich inkorporiert, so daß eine atomare S‐Bedeckung mit ΘS = 1/7 zurückbleibt, die eine (\documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt 7 {\rm x}\sqrt 7 $\end{document}) ± 19,1°‐Überstruktur ausbildet. Diese Struktur wird auch nach Hochheizen einer bei 320 K hergestellten (2 × 2)‐SO‐Sättigungsbedeckung mit ΘSO = 0,5 sowie nach SO2‐Exposition bei T > 500 K beobachtet, wo sie Bedeckungsgraden ΘS von 3/7 und 2/7 entspricht. Weiterhin wurden der „Vergiftungseffekt”︁ durch adsorbierten Schwefel auf die dissoziative Adsorption von Sauerstoff und die S‐Oxidation durch Hochheizen einer OS‐Koadsorptionsphase untersucht. Insgesamt wurden folgende reaktionskinetische Parameter (Aktivierungsenergien und Vorfaktoren) bestimmt: magnified image.
Non‐Maxwellian Characteristics of the Energy Distribution of Thermal Electrons in the Upper Atmosphere
Authors: Amemiya H. 
Published: May 2007

AbstractThe Result of Measurements of the energy distribution of thermal electrons in a midlatitude ionosphere is presented. A comparison is made in particular between the characteristics at sunrise and sunset periods because of the effect of vibrationally excited nitrogen molecules.At sunrise the distribution has a little‐irregularity but the middle and higher energy parts (0.2‐0.5 eV) deviate from the Maxwellian distribution only slightly at all heights. The electron temperature varies from 900 K to 1300 K between 130 km and 300 km. These values are higher than the kinetic temperature of neutral particles but comparable with the theoretical values of the vibration temperature of N2.At sunset small bumps due to non‐thermal electrons are seen on the high energy tail between 108 and 160 km, their density being from 5 × 10−3 to 1 × 10−2 of that one of the thermal electrons. Above 170 km (F‐layer) the deviation of the distribution from the Maxwellian one becomes smaller. The electron temperature varies from 500 K to 900 K between 100 km and 220 km. These values are higher than the kinetic temperature but lower than the theoretical values of the vibration temperature of N2. A mechanism of the appearance of non‐thermal electrons is considered to be due to super‐elastic collisions with vibrationally excited N2.
High‐Field Carrier Transport in Inhomogeneous Semiconductors
Authors: Böer K. W. 
Published: May 2007

AbstractThe carrier transport in inhomogeneous solids is reevaluated in respect to the differences between a built‐in field within a space charge region and an external field, and related to differences in carrier redistribution and carrier heating, resulting in a different field‐dependence of the mobility. With the assistance of electrostatic and electrochemical potential distributions the regions of substantial carrier heating can be identified as regions in which the current is carried by diffusion only (DO), or by drift only (DRO) in forward (or low reverse), and in high reverse bias respectively, and are distinguished from the region of a major electrostatic potential drop (Boltzmann region) in which the net current is small compared to drift and diffusion. In junction devices major carrier heating does only occur in DO‐ and DRO regions, and only for minority carriers.
NMR‐spektroskopische und Röntgen‐diffraktometrische Untersuchungen zur Wechselwirkung zwischen Cellulose und Natronlauge
Authors: Philipp B. , Fink H.‐P. , Kunze J. , Frigge K. 
Published: May 2007

AbstractStruktur und Bildungsweise von Alkalicellulose werden mittels CP/MAS‐13C‐NMR‐Spektroskopie, 23Na‐NMR‐Spektroskopie und Röntgen‐Weitwinkelstreuung untersucht. Die Wechselwirkung der Natronlauge mit Cellulose führt zu Konformationsänderungen am Makromolekül, die im Zusammenhang mit irreversibel verlaufenden Gitterumwandlungen diskutiert werden. Die Bedeutung der übermolekularen Struktur des Polymers wird anhand des Modelles uneinheitlicher Fransenfibrillen demonstriert.
A Modification of Projective Spacetime by Finite Self‐Interaction Models of Virtual Leptons and Quarks and the Electroweak GWS Standard Model
Authors: Scheurich H. 
Published: May 2007

AbstractFrom the projective Dirac equation in a six‐dimensional Kleinian space R(3, 3) are derived finite‐rotation‐group models as self‐interaction models of virtual leptons and quarks. The quaternion group underlying them is considered as a substructure group of projective spacetime. A finite hypersherical carrier of the self‐interaction models is embedded into projective spacetime by means of the Planck length L0 = (ħG/c3)1/2 as a physical unit length. The corresponding modification of metrics in the Planck domain becomes apparent to be equivalent to the rǒle of the Higgs field in the electroweak GWS standard model.
Unification Based on ElectromagnetismA Simple Composite Model of Particles
Authors: Barut A. O. 
Published: May 2007

AbstractThe complex machinery of gauge theories and QCD is not the only possible avenue to understand the physics of elementary particles. There is another simple and more direct approach based on absolutely stable particles as constituents of all other particles. Mathematically the ensuing group structure is identical to the quark‐lepton model, but the dynamics and the underlying physics is different. How all forces of elementary particles are already dynamically unified under electromagnetism is discussed.
Description of Pulse Propagation in Optical Strip Waveguides by the Generalized Nonlinear Schrödinger Equation
Authors: Eichhorn H. 
Published: May 2007

AbstractTaking into consideration the transverse confinement, the dispersion of the linear as well as of the nonlinear part of the refractive index and the nonlinear interaction of the electromagnetic field with the guiding material, the yielding equation for the envelope function of the fundamental mode propagating in a strip waveguide is the generalized nonlinear Schrödinger equation. In contrast to the nonlinear Schrödinger equation, solitons of the generalized nonlinear Schrödinger equation exist in the regimes of negative and positive group dispersion and are asymmetric.
Apodisation für die beugungsbegrenzte Abbildung des Achsenpunktes mit rotationssymmetrischen optischen Systemen
Authors: Haferkorn H. 
Published: May 2007

AbstractEs wird eine Pupillenfunktion vorgeschlagen, mit der das Beugungsintegral unter Berücksichtigung der Apodisation geschlossen lösbar ist. Die Apodisation nach einer Zylinderfunktion bringt eine größere Intensität im Zentrum des Beugungsbildes und ein besseres Auflösungsvermögen als die Apodisation nach einer Gauß‐Funktion mit sich.
Hermitizität und Eichinvarianz
Authors: Treder H.‐J. 
Published: May 2007

AbstractDie Forderungen der Hermitizität und der Eichinvarianz werden in der Hermiteschen Relativitätstheorie (HRT) durch verschiedene Auffassungen über das Wesen der Hermitizität in unterschiedlicher Weise dargestellt. Aber alle hermiteschen Gleichungssysteme müssen die schwachen Einsteinschen Gleichungen erfüllen, welche den Einstein‐Schrödingerschen Gleichungen äquivalent sind.
Dispersion and Spontaneous Current Phenomena in NH4Cl Single Crystals
Authors: El‐Kabbany F. 
Published: May 2007

AbstractThe effect of frequency and d.c. biasing on the dielectric constant of NH4Cl single crystal samples was studied. A dispersion phenomenon was observed in the frequency range 105‐108 Hz. This was attributed to a piezoelectric effect.The present study revealed that a spontaneous electric current of the order 10−12 A was found to accompany the order ‐ disorder process. This current showed a clear singnal in the phase transition region of the order‐disorder transition III‐II of NH4Cl. This singnal was well controlled by the application of a polarizing electric field so that its amplitude could be increased, decreased, vanish or even reversed by the application of an appropriate external electric field.
Energy Levels of the Single Excited States in the Boron Isoelectronic Sequences
Authors: El‐Sherbini Th. M. , Mansour H. M. M. , Farrag A. A. , Rahman A. A. 
Published: May 2007

AbstractEnergy levels of the single excited 1s22s2ns (2S), 1s22s2np (2P), 1s22s2nd (2D) and 1s22s2nf (2F), n = 3‐8 states for the boron isoelectronic sequence are calculated using the simple configuration Hartree‐Fock method. Good agreement is obtained between our results and previous experimental and theoretical data.
Nuclear Collective Rotations and the Single Particle Motion in a Rotating Potential
Authors: Osman A. Ahmed , Allam M. A. 
Published: May 2007

AbstractThe heavy and medium nuclei with angular high momentum are reconsidered. The study of these nuclei is introduced according to the way of building up the angular momentum. At high angular momentum, the moments of inertia of that nuclei are investigated. A study for the path of the Yrast spectra is given in the deformation space. Then, the nuclear collective motions and the single particle motion in a rotating field are considered and studied in both cases of the absence and the presence of pair correlations.
Neutron Distributions in Ducted Egyptian Ilmenite Concrete Shields
Authors: Makarious A. S. , Ahmed F. M. Sayed 
Published: May 2007

AbstractIn this work the measurement of neutron distributions along and normal to the axis of air filled ducts with different duct diameters pierced in ilmenite concrete have been carried out. The data show the dependence of the neutron doses on the duct length and diameter. The neutron distributions along the duct axis were compared with the corresponding distributions in solid ilmenite concrete.Semiempirical formulae have been derived fitting well with the experimental data obtained.
The Weak Energy Condition and Singularities in Classical Free N = 1 Supergravity
Authors: Pullin Jorge 
Published: May 2007

AbstractWith the use of the modification of the weak energy condition for theories with torsion developed by Hehl, we analyse classical free N = 1 supergravity in the hope that spin‐spin contact interactions may avert singularities, as happens in the neutrinic case. We find that this does not happen, since the appearence of singularities is conditioned by the cosmological model of the gravitino field in consideration. We present a very simple singularity free model for a spatially homogeneous Rarita‐Schwinger field in a Robertson‐Walker spacetime.
Shower Particle Multiplicity Distribution in High Energy Nuclear Reactions
Authors: Hussein M. T. , Hassan N. M. , Hegab M. K. 
Published: May 2007

AbstractThe multiplicity distributions of charged shower particles in high energy reactions are studied in the framework of a statistical model based on the approximation of the phase space integral. The model is first applied to the proton‐proton collisions and then further extended on geometrical basis to include proton‐nucleus and nucleus‐nucleus collisions. Although the model is parameter free, it gives quite satisfactory results in comparison with experimental data.
Analytical I‐Dependent Folding Potential According to Alpha‐Cluster Model ‐I
Authors: Hassan M. Y. M. , Comsan M. N. H. , Tageldin I. M. A. 
Published: May 2007

AbstractThe folding model is applied to calculate the nucleon and alpha‐nucleus interaction for 12C and 16O. The matter densities are obtained using the alpha‐cluster model. Analytical l‐dependent expressions for the folding potential as well as the deformation parameters are given. The effect of applying different nucleon‐nucleon forces is discussed.
The Internal Bremsstrahlung Accompanying the β‐Decay from 185W
Authors: Basha A. M. , Ragab H. S. , El‐Konsol S. , Osman O. M. 
Published: May 2007

AbstractThe internal bremsstrahlung (IB) spectrum accompanying the β‐decay from 185W radionuclide has been measured. The obtained spectrum was analyzed into its constituting gamma lines taking into account all the proper corrections. The analyzed spectrum was compared with those theoretically calculated. The experimental results for the IB probability were found to be in good agreement with theoretical calculations especially with the shape corrected modified KUB theory of Nilsson up to 357.7 keV.
The Influence of Cation Substitution on the Magnetic Behaviour of Magnesium Ferrite
Authors: Fayek M. , Elnimr M. , Nada N. , Saleh H. , Eid Y. 
Published: May 2007

AbstractNew polycrystalline specimens of the ferrites Mg1.5Fe1Si0.5O4, Mg1.5Fe1Ge0.5O4, Mg1.5Fe1Ti0.5O4 and Mg1.66Fe1Sb0.33O4 have been prepared and studied by nuclear gamma ray resonance technique, over a wide temperature range. All samples are monophasic spinel type ferrite with cubic symmetry. Mössbauer effect spectra of the composition containing Si4+ or Ge4+ show magnetic hyperfine splitting at room temperature, and Néel transition points are found around 750 and 570 K for the two compounds respectively. The spectrum of Mg1.5Fe1Ti0.5O4 is paramagnetic at 300 K while at 78 K shows a superposition of a broad six lines pattern and a central quadrupole doublet. The sample with pentavalent antimony exhibits a strong ferromagnetic relaxation at 78 K where it shows six broad lines with enhancement of the two inner lines as the temperature is risen. For all compositions the Mössbauer effect parameters are determined and cation distributions are deduced and its effect on the magnetic behaviour is discussed.
Determination of Neutron Spectra in a Graphite Sphere for Fusion Reactor Studies
Authors: Bashter I. B. , Cooper P. N. 
Published: May 2007

AbstractCalculated and experimental results for the neutron spectra at different radii in a graphite sphere irradiated with 14.1 MeV neutrons were shown to be in satisfactory agreement over the energy range 14.1 to 1.8 MeV neutrons. A group of curves were constructed which gives the radius of a graphite sphere shield required to attenuate the neutron intensity to a certain value. The data set used in the present work, with carbon‐12 cross section, is shown to be useful for spherical calculations.
Processes with Higgs Scalar Bosons in External Electromagnetic Fields
Authors: Ternov I. M. , Rodionov V. N. , Studenikin A. I. 
Published: May 2007

AbstractIn this paper we consider the processes with real and virtual Higgs scalar H‐boson in the presence of an external constant electromagnetic field. We get formulae for the probability of the H‐boson emission by a charged lepton and the field radiative H‐boson effects (i.e. the contribution to the mass and the anomalous magnetic moment of the lepton.
Detailed I.R. Study of the Phase Transition in the System AgNO3‐Fe(NO3)3
Authors: El‐Kabbany F. , Taha S. , Tosson M. 
Published: May 2007

AbstractA complete infrared study of the mixed crystal system of AgNO3 and Fe(NO3)3 is carried out in the region 400–4000 cm−1. The study includes internal fundamental normal vibrations of the NO3− ion in the ordered and disordered phases of AgNO3 at different values of the ferric concentration, I.R. spectra, spectral band shape intensities, and frequencies of the internal modes as functions of the ferric ion concentration. Special attention is paid to bending mode, combination mode, asymmetric stretching mode, and over‐tone. The rotational energy barrier is determined at different concentration of the ferric ions in the system of AgNO3‐Fe(NO3)3.
On the Einstein Relation in Ternary Semiconductors in the Presence of Crossed Electric and Magnetic Fields
Authors: Mondal M. , Ghatak K. P. 
Published: May 2007

AbstractWe investigate theoretically the Einstein relation for the diffusivity‐mobility ratio of the electrons in ternary semiconductors at low temperatures in the presence of crossed electric and quantizing magnetic fields on the basis of threeband Kane model. It is found, taking n‐Hg1‐xCdxTe as an example, that DMR shows an oscillatory magnetic field dependence. Besides, the DMR increase both with increasing electron concentration and decreasing alloy composition respectively.
A First Order Generalized Thomas‐Fermi Approximation for the Electron Density in Inversion Layers
Authors: Übensee H. , Paasch G. 
Published: May 2007

AbstractAn operator evaluation of the one‐particle density matrix of a degenerate system of independent particles in first order with respect to the gradient of the potential developed by Macke and Rennert yields an analytic expression for the particle density. This method is extended here to potentials with an infinite step and to finite temperatures – a situation which is characteristic for inversion electrons in MIS‐systems. The resulting density can be expressed as the Airy transform of the zeroth order (local density approximation). The first order yields both the tunneling into the classically forbidden region and oscillations of the density near the step of the potential. The operator evaluation of the density matrix is shown to be equivalent to solving a Schrödinger like equation. The first order density yields results for the subband structure of (100)Si inversion and accumulation layers at OK in remarkable agreement to density functional calculations of Ando.
In‐Beam γ‐Ray Studies of Band Structures in Ho151
Authors: Mansour N. , Bayomy T. , Awwad Z. , Farhan A. 
Published: May 2007

AbstractWe reported here the level structure in the ood proton nucleus Ho151. High spin states in Ho151 have been populated in the Sn122 (Cl35, xyzγ) reaction. The level structure has been established up to an energy of 9.9 MeV and spin value I = 63/2. The systematic behavior of the level pattern of Ho151 nucleus is discussed in the context of the high‐spin structure in the neighbouring nuclei. Most of the proposed level configurations can be explained by the coupling of h 11/2 protons to f 7/2 and/or h 9/2 neutrons.
IR Spectral Analysis of the Mixed Crystal System of AgNO3 and Sr(NO3)2
Authors: El‐Kabbany F. , Taha S. , Tosson M. 
Published: May 2007

AbstractIR spectroscopy is utilized to analyse the mixed crystal system of AgNO3 and Sr(NO3)2 in the ordered phase II and disordered phases of silver nitrate.The study aims mainly to clearify the change and the affect of partial replacement of Ag+ ion by Sr++ ion in the mixed crystal system of the two metal nitrates. The change in the rotational energy barrier of the nitrate group was also checked.
Mass Distributions and Charge Dispersion for the Nuclear Fission
Authors: Osman Ahmed , Abdel‐Latif A. M. 
Published: May 2007

AbstractThe theory of nuclear fission is reconsidered by introducing the charge asymmetry in the asymmetric two center shell model as a dynamical collective coordinate. The quantum mechanical fluctuations, which are accompanied with the collective motion as a function of the mass asymmetry, are responsible for the mass distributions in nuclear fission. Numerical calculations are carried out for the mass distributions and charge dispersions for the nuclear fission of the 236U and 238U nuclei. The present obtained theoretical calculations are in good agreement with the experimental measurements.
Huygens' Principle on Petrov Type D Space‐Times
Authors: Wünsch V. 
Published: May 2007

AbstractGeneralizing the recently by J. Carminati and R. McLenaghan [2] obtained results it is shown that there exist no Petrov type D space‐times on which the conformally invariant scalar wave equation, or Maxwell's equations, or Weyl's equations satisfy Huygens' principle.
Dielectric and Polarization Studies of KNO3 Thin Layers
Authors: El‐Kabbany F. , Mahrous S. 
Published: May 2007

AbstractUltrapure and homogeneous KNO3 thin layers are subjected to dielectric and polarization measurements over a wide temperature range. The dielectric results obtained are discussed on the assumption of probable formation and migration of vacancies. The variation of polarization with the applied field was found to be nonlinear and the polarization reversal occurs at a critical value of the applied field of strength 11 kV/cm. This value is in good agreement with the value of the coercive field determined previously by the ferroelectric hysteresis loops.
Mathematical Foundations of the Dimensional Method
Authors: Rufa G. 
Published: May 2007

AbstractWe summarize and discuss important mathematical foundations concerning the dimensional method. To this end we carefully discuss the assumptions as well as the derived fundamental statements. We define and investigate the uniqueness of the ϵμνστ tensor in n dimensions and, related to this, the uniqueness of γ5. Furthermore, we develop an algorithm which allows the calculation of a set of scalar multi‐loop integrals with masses in a systematic way. To demonstrate and test the algorithm we rederive a set of scalar integrals which are important in calculations at the one and two loop level.
Electrical and Thermal Properties of NH4BrxCI1‐x Single Crystal
Authors: El‐Kabbany F. , Tosson M. , Taha S. 
Published: May 2007

AbstractThe effect of partial replacement of Cl− ions by Br− ions in the mixed system of ammonium chloride and ammonium bromide during a set of thermal heating cycles is studied. The study includes electrical measurements (d.c. resistivity, dielectric constant and the spontaneous thermal current), differential thermal analysis (DTA) and dilatometric thermal analysis in the temperature range −60 °C up to 30°C. The results show a large change in the various measured parameters sensitive to thermal agitation process and to the presence of the bromine ions in the mixed crystal system close to the morphotropic boundary x = 0.5. At this boundary the temperature region of the ordered phase extended by about 28°C. The transformation enthalpy was reduced in such case to 41.3 cal/mol. According to the different experimental data of the system NH4BrxCl1‐x, a phase diagram was proposed. This phase diagram predicted that the order‐disorder phase transition point changed widely according to the value of x and reached −2°C when the mixed crystal system contained 50% of Br− ions.
Identification of Single‐Particle Configurations at Very High Spin in Some Rare‐Earth Nuclei
Authors: Mansour N. , Bayomy T. , Awwad Z. 
Published: May 2007

AbstractThe nuclear behaviour at high angular momenta is studied by γ‐rays emitted in (HI, Xn) reaction. The study of very‐high spin states in 153Ho via discrete‐line γ‐ray spectroscopy and a comparison between the partial decay schemes of 153Ho and the neighbouring 152Dy and 154Er nuclei are discussed in the context of the high spin structure. Second, we present comments on some phenomena observed at high spin states in 153Ho and 152Dy nuclei.
A Model of Resonance Scattering on Curved Quantum Wires
Authors: Exner Pavel 
Published: May 2007

AbstractA model of electron motion in a curved quantum wire of a finite length 2D attached to a pair of macroscopic electrodes is studied. Regarding the problem as a two‐dimensional one, we model the electrodes as halfplanes and the quantum wire as a line segment joining them; it supports a potential which is a combination of a constant transversal‐mode energy and an attractive curvature‐induced term. We show that the bound states which may be present at an infinite quantum wire turn into resonances and that spectral concentration is valid as D → ∞.