bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transverse Spatial Resolution of Thermo–Optical Hysteresis in CdS
Authors: Nguyen H. X. , Egorov V. D. , Harendt A. , Nazvanova E. V. 
Published: July 2007

AbstractTransmission beam‐profile variation thermally induced in CdS crystals is investigated at room temperature using a cw‐Ar+‐laser and an electro‐optical modulator to produce pulses in the ms range. The formation and development of a plateau (or a ring) of the brightness in the transmitted beam are observed which strongly depends on the actual temperature of the sample. Calculations for a thin sample based on the two‐dimensional heat transport equation yield a good agreement with the experimental results.
Self‐Trapped Exciton Emission of SnSO4
Authors: Donker H. , Smit W. M. A. , Blasse G. 
Published: July 2007

AbstractThe luminescence properties of SnSO4 and BaSO4–Sn2+ are reported and discussed. At low temperatures both compounds show Sn2+ luminescence. In SnSO4 energy transfer to defect centres occurs at higher temperatures. A comparison is made with the luminescence of related systems.
Electrons in MIS Inversion and Accumulation Layers. Exchange and Correlation Effects within a Modified Thomas‐Fermi Theory
Authors: Übensee H. , Paasch G. , Bundfuss D. , Zöllner J.‐P. 
Published: July 2007

AbstractFor the calculation of the electronic structure of inversion and accumulation layers in MIS‐structures self‐consistent methods based on the density functional formalism are well developed. The numerical effort for such calculations is drastically reduced by a modified Thomas‐Fermi method developed in the last years. The method is a unique one for both, inversion and accumulation layers and well suited for modeling of MIS‐devices. It is proved that this method is very accurate. Several problems are solved first by using it, but till now always neglecting exchange and correlation effects. It is shown how one can include them as a part of the effective potential into the modified Thomas‐Fermi method by using a simple calculation scheme. A systematic investigation of the influence of exchange and correlation effects on the complete electronic sub‐band structure is presented for several III–V‐semiconductors at low temperature and for Si at both room and low temperature.
Thermal Parameters and Probability Density Functions of the Narrow Gap Semiconductor Bi2Te3 under Hydrostatic Pressure
Authors: Kullmann W. , Rauh H. , Geick R. , Steigenberger U. , Kuhs W. F. 
Published: July 2007

AbstractThe thermal parameters and the probability density functions of the atoms in the narrow gap semiconductor Bi2Te3 are investigated by neutron diffraction experiments under hydrostatic pressure. The results show rather complex intrasandwich bonding properties of the atoms in this sandwich structure. Especially Bi shows relatively large vibration amplitudes parallel to the trigonal axis in contradiction to former X‐ray studies. The experiments show evidence for healing effects of crystal distortions under hydrostatic pressure.
Short‐Range Order and Atomic Displacements in Ni–20 at% Cr Single Crystals
Authors: Schönfeld B. , Reinhard L. , Kostorz G. , Bührer W. 
Published: July 2007

AbstractNi–20 at% Cr single crystals aged at 741, 828, and 973 K for up to 480 h are investigated by elastic diffuse neutron scattering. The contributions due to short‐range order and atomic size effect are separated by a least‐squares fitting procedure. The short‐range order with diffuse intensity maxima at l 1/2 0 positions increases with decreasing ageing temperature. In comparison, the intensity due to atomic displacements is weak. For the three ageing temperatures investigated the effective pair potentials, determined from the Clapp‐Moss high temperature approximation as well as with an inverse Monte‐Carlo method, are very similar.
Stress‐Induced Dichroism of the Vibrational Lines and Phonon Sidebands of SH− Centres in CsBr
Authors: Otto J. 
Published: July 2007

AbstractParaelastic alignment of SH− centres in CsBr leads to a stress‐induced dichroism of the infrared absorption lines and their phonon sidebands. The principal values of the elastic dipole tensor are determined from quantitative infrared measurements under uniaxial stress. The centres turn out to be 〈100〉 oriented and have a disk‐shaped elastic dipole tensor. The stress‐alignment is used to determine the polarization of the phonon sidebands with respect to the molecular axis. Those irreducible representations, by which phonons and localized modes mainly couple to the intramolecular vibration, are derived with the help of group‐theoretical considerations. Selection rules for the appearance of particular phonons in the sidebands are discussed.
Thermoelectric Coefficients of a Limited 2D Gas in Quantizing Magnetic Field
Authors: Karyagin V. V. , Lyapilin I. I. , Dyakin V. V. 
Published: July 2007

AbstractThe dependence of Hall conductivity and diagonal component thermopower of a limited 2D gas in high magnetic field is calculated using Kubo's formula. The main attention is paid to the effect of sample edges which are responsible for the universal properties of two‐dimensional systems (represented by inversion layers) as e.g. unusual properties of the thermopower at low temperatures.
Study of the Polarized Light Absorption on Electrically Charged Thin Films of Copper Monocrystals by ECPA
Authors: Romanowski S. 
Published: July 2007

AbstractThe relative absorbed power of polarized light is calculated for copper thin films by means of Green's functions technique and ECPA approach. A mechanism of polarized light absorption on the electrically neutral as well as electrically charged films is analysed. It is concluded that the crystallographic structure and a volume charge parameter \documentclass{article}\pagestyle{empty}\begin{document}$ \bar n_s $\end{document} play the most important role in light absorption.
Impurity Binding Energies in Heterostructures. Two‐Band Model
Authors: Albuquerque E. L. , Costa W. B. 
Published: July 2007

AbstractA transfer‐matrix treatment is presented for a one‐dimensional semiconductor heterostructure to discuss its electronic density of states. A two band formalism is considered with direct gap between the valence and conduction bands. The system is described by a tight‐binding Hamiltonian, with interactions between first neighbours. Using numerical data of AlxGa1−xAs–GaAs some interesting features in its electronic structure frequencies around 2 eV are shown.
Quantized Photoemission from Quantum Wells in Ultrathin Films of Wide‐Gap Semiconductors in a Tilted Magnetic Field
Authors: Majumdar C. , Maity A. B. , Chakravarti A. N. 
Published: July 2007

AbstractAn attempt is made to investigate the effects of a tilted quantizing magnetic field on the photoemission from quantum wells in ultrathin films of wide‐gap semiconductors, taking n‐type GaAs as an example. The photoemission exhibits an increasing step‐like variation with increasing photon energy and is also found to have oscillatory dependence on the magnetic field, its orientation, and the film thickness. Strikingly, the dependence of the emission on film thickness, for photon energies considerably lower than the electron affinity, shows that it gets quantized.
A Self‐Consistent Method for Evaluating the Effective Mass of Electrons in Metals
Authors: Mishra L. K. , Tripathy D. N. 
Published: July 2007

AbstractA self‐consistent method for determining the effective mass, m*, of electrons in metals is presented. This is done through the evaluation of the electronic specific heat of metallic solids. The calculated values for m* agree remarkably well with the experimental data for sodium and potassium.
The Influence of Phonons on Dielectric Properties of Molecular Crystals
Authors: Tošić B. S. , Šetrajčić J. P. , Mirjanić D. Lj. 
Published: July 2007

AbstractIn molecular crystals whose inversion centrum does not coincide with that of the molecule, the Hamiltonian of exciton–phonon interaction is a bilinear form in exciton as well as in phonon operators. This leads to the hybridization of excitons and phonons into new excitations. The dielectric constant is analysed in the system of hybrid excitations. The frequency dependence of dielectric constant is analysed numerically for different values of wave vector. A comparison of dielectric constants of molecular crystals with and without phonons is made. It is shown that the presence of phonons changes the trend and shifts the singularity towards higher frequencies.
Exciton Propagation in the Field of a Driven Vibration
Authors: Marlow F. , Esser B. 
Published: July 2007

AbstractThe propagation of excitons in the presence of a strongly excited vibration is considered using the generalized master equation (GME) approach. A model is developed in which the amplitude of the vibration is subjected to stochastic variations modelling the fluctuations of the energy supply into the driven mode. The corresponding GME kernel is calculated and the parameters separating the regions of coherent and incoherent exciton propagation are discussed. It is shown that the presence of a non‐equilibrium vibration substantially modifies the transport as compared to the interaction with equilibrium phonons.
Energy Distribution of Trapping Centers in Vitreous GeSc3 as Obtained from Transit Time Measurements in the Temperature Range 60 to 300 K
Authors: Calas J. , Maksoud S. M. Abdel , Averous M. 
Published: July 2007

AbstractThe decreasing parts of transient currents associated with photocarriers created by convenient light on one side of the samples are investigated as a function of the temperature in the range 60 to 300 K. From the slope of the two corresponding parts, two parameters, α1 and α2 are deduced. From their behavior several trapping center energy distribution models are discussed. The trapping center density is found to obey the law Nt(E) = CE exp [−E/kT]2. The width of the trapping center energy distribution is about 10 meV and their density reaches 1021 cm−3.
Localization in a System of N Coupled Chains – Recursion Method. II. Explicit Calculation for Two Coupled Chains
Authors: Kasner M. , Weller W. 
Published: July 2007

AbstractOn the basis of a previously derived general expression the localization length of an electron moving along two weakly coupled chains is analytically calculated. In the weak scattering limit an explicit equation is derived for the asymptotic probability density of the five parameters characterizing two matrices ϱ and ϰ which determine the localization length. This equation is solved in the limit of “strong” coupling (∣t⟂∣ · l/(∣t∥∣ · sin k) ≫ 1, although ∣t⟂∣/∣t∥∣ ≪ 1). The localization length is lloc(2) = 1.7756l. It is shown that also for arbitrary number of chains and arbitrary dimension of the cross‐section the ratio of the strength of disorder and the chain coupling is the essential parameter.
Transport Properties of Quasi‐Two‐Dimensional Mo4O11 Crystals
Authors: Inoue M. , Ōhara S. , Horisaka S. , Koyano M. , Negishi H. 
Published: July 2007

AbstractThe electrical resistivity under hydrostatic pressure up to 1.0 GPa, Hall effect, magnetoresistance, and thermoelectric power are measured over the temperature range from 1.5 to 300 K for both, orthorhombic γ‐Mo4O11 and monoclinic η‐Mo4O11 crystals with quasi‐two‐dimensional structures. All these properties show anomalies associated with the charge density wave (CDW) transition; particularly the hydrostatic pressure enhances the CDW instabilities through the increased electron–phonon interaction and partial nesting of the Fermi surfaces. It is also found that both, electrons and holes contribute to the conduction processes, for which a qualitative discussion is made.
Piezoresistance in CdIn2S4
Authors: Nakanishi H. , Isomae M. , Endo S. , Irie T. 
Published: July 2007

AbstractPiezoresistance of n‐type CdIn2S4 single crystals is measured for various directions of the crystal axis. The values at room temperature are isotropic but large, in particular for degenerate samples, compared with those for materials which have spherical energy surfaces. The large values of the piezoresistance of CdIn2S4 is found to be due to its long time relaxation. The values measured immediately after the application of the stress are small and also isotropic, consistent with the spherical band model and are π11 = −17.2 × 10−7, π12 = 3.24 × 10−7, and π44 = −17.2 × 10−7 cm2/N. The same results are obtained by measurements at low temperatures. The time relaxation of the piezoresistance may be due to trapping centers in the crystals the depth of which depends on the stress and this is confirmed experimentally by measurements of the thermally stimulated currents under various strengths of the stress.
The Luminescence of Palladium‐Doped Silicon
Authors: Thomas V. , Barrau J. , Brousseau M. , Kirouni K. , Couloumiers G. 
Published: July 2007

AbstractIt is observed for the first time, the photoluminescence of palladium in silicon; the zero‐phonon line, located at 1.0084 eV, is analysed under magnetic field. It shows similitude with the 0,811 eV line of a platinum defect, preceedingly reported. It is concluded that the palladium atom is in the substitutional lattice site with neutral charge state.
Multiphoton Excitation of the 520 nm Luminescence Band in MgO:Al
Authors: Dunphy K. , Duley W. W. 
Published: July 2007

AbstractMgO:Al crystals illuminated with pulses from a XeCl laser luminescence strongly in broad bands centered at 520 and 736 nm. The 520 nm band appears to be due to luminescence from F centers and exhibits a strong non‐linear dependence on XeCl laser intensity. On log–log plots of luminescent intensity vs. pump intensity, straight line segments with I4 and I6 dependence are observed, suggesting that the 520 nm emission is pumped by energy transfer from bi and tri‐excitons. Saturation of this emission at high laser flux appears to be due to electron or hole trapping at vacancy defects.
Interatomic Potentials with Multi‐Body Interactions
Authors: Haliciogli T. , Pamuk H. O. , Erkoc S. 
Published: July 2007

AbstractVarious model potentials comprising two‐ and three‐body interactions are analyzed comparatively. In this study Tersoff (T), Tersoff‐Dodson (TD), Stillinger‐Weber (SW), and Pearson‐Takai‐Halicioglu‐Tiller (PTHT) potentials are included and their capabilities in reproducing various bulk, surface, and small cluster properties of silicon are investigated. For a proper comparison properties of small Si clusters are also calculated in this work using the PTHT function. Applicability and limitations of each potential are delineated and discussed. In general, structural properties calculated by these functions are found to be in better agreement with experiments than corresponding energy‐related properties.
On Lorentz Symmetries in Solids
Authors: Günther H. 
Published: July 2007

AbstractSoliton properties of kinks on dislocations allow a definition of natural standards for the measurement of length and time which are inherently related to the lattice structure. If dynamical processes such as wave propagation and the motion of screw dislocations are expressed in terms of standards of such a kind, Lorentz symmetries associated with sound propagation become evident.
Center Manifold and Phase‐Ordering Dynamics for the Onset of Nonequilibrium Organizations
Authors: Fernández Ariel 
Published: July 2007

AbstractA general derivation is provided for transients or induction periods for the onset of organized temporal dissipative structures. The treatment applies in the case where the phase‐space contraction occuring beyond criticality can be accounted for by the existence of a locally‐attractive and locally‐invariant center manifold. Especially the case is considered of a reactive open system which operates far from equilibrium and sustains a hard‐mode instability. This class of systems is studied in the context of fluctuation amplifications leading to phase‐ordering dynamics, as in the case of spinodal decompositions and nucleation phenomena in ferromagnets and superconductors.
A Simple Scheme for Studies of Surface Phonons of Covalent Semiconductors. II. Surface Phonons at Ideal and Relaxed Si(110) Surface
Authors: Lin Zijing , Wang Kelin 
Published: July 2007

AbstractOn the basis of some formulae for force constants calculation and using ten‐atomic‐layer slab, surface phonon dispersion curves along symmetry lines \documentclass{article}\pagestyle{empty}\begin{document}$ \overline \Gamma $\end{document}X, XS, SY and Y\documentclass{article}\pagestyle{empty}\begin{document}$ \overline \Gamma $\end{document} in two dimensional Brillouin zone are displayed. For relaxed surface an interesting surface mode is found, which cannot be understood in the elastic‐continuum approximation even for long wavelength limit.
A SIMS Analysis of Hydrogen Involved Reactions on InSb Surfaces
Authors: Wolf B. , Zehe A. 
Published: July 2007

AbstractAn analogy is established on physical grounds between an ion‐beam damaged cleavage plane and a ‘transient’ imperfection rich growing MBE‐layer. Chemical reactions between the former and hydrogen are analyzed using SIMS as an analytical tool. A high chemical reactivity of the ion‐beam damaged InSb (110) cleavage plane with hydrogen is found and explained by the assumption that the generated imperfections induce molecular dissociation into atomic hydrogen that easily reacts with the surface. Transient imperfections in growing MBE‐layers are suggested to play a similar role with respect to an increased reactivity found during MBE growth.
Dynamical Image Potential of a Point Charge Approaching a Metal Sphere
Authors: Thoai D. B. Tran , Zeitler E. 
Published: July 2007

AbstractThe dynamical image potential for a point charge approaching a metal sphere is calculated; it shows a pronounced dependence on the velocity and on the impact parameter of the moving charge. The moving of the point charge causes a change in the value of the image potential and renders it finite at the metal surface. For higher velocities the dynamical image potential tends to zero. However, for large distances between point charge and center of the sphere, the dynamical image potential hardly deviates from the classical image potential.
The Study of Energy Band Structure and Chemical Bonding in Yttrium Carbide, Yttrium and Strontium Dicarbides by the LMTO and Xα DV Method
Authors: Zhukov V. P. , Medvedeva N. I. , Novikov D. L. , Gubanov V. A. 
Published: July 2007

AbstractThe energy band structures of yttrium carbide, yttrium and strontium dicarbides are studied by the LMTO‐method. The cohesive energies and the total and partial pressures are calculated. The local electronic structure of yttrium dicarbide is studied by the Xα discrete variational method; the cluster Y6C2 which includes the group C and all the nearest neighbours of this group is used in this study. The results of this calculations are used to analyse the chemical bonding and some properties of the compounds. It is shown that the main contribution to the chemical bonding between C group and yttrium atoms is provided by the orbital of the eg‐local symmetry which belongs to the zone of metallic state. In the SrC2 this orbital is empty which explains the instability of its crystal lattice.
Energy Band Structure of Phenazine N Oxide and Phenazine N Dioxide. Candidate Materials for Organic Photovoltaic Devices
Authors: Kumar B. , Agarwal H. 
Published: July 2007

AbstractA tight binding method with SCF AO's is employed to investigate the energy band structure of phenazine N oxide and phenazine N dioxide. The mode of charge transport along various crystallographic directions is examined in the light of existing theories of charge transport in organic semiconductors. The effect of heteroatoms on the mode of charge transport is discussed. Phenazine N Oxide and phenazine N dioxide are found to be candidate materials for organic photovoltaic devices.
Theory of the Superconductivity in Two Energy Band Systems
Authors: Ciobanu G. , Corcotoi I. , Fazakas A. B. 
Published: July 2007

AbstractFunctional integral techniques are utilized in the study of the superconductivity in a system of electrons containing both, a large band and a narrow‐one with large effective mass and an attractive coupling. After deducing the free energy functional, the equations for the order parameter and transition temperature are obtained and discussed. Finally the electronic specific heat and its jump at Tc are calculated.
Electronic Properties of Liquid TlGeTl2Se4 and TlSnTl2Se4 Systems
Authors: Ishikawa H. , Kameda Y. , Uemura O. , Satow T. 
Published: July 2007

AbstractMeasurements of the electrical conductivity, magnetic susceptibility, and thermoelectric power for the liquid TlGeTl2Se4 and TlSnTl2Se4 systems are made in wide temperature and composition ranges. It is observed that the conductivity for both the systems has a minimum near the composition of 66.7 mol% Tl. However, the results of magnetic susceptibility reveal that the metalnonmetal transition of the present two systems occurs not at 66.7 mol% Tl but at 80 mol% Tl. The temperature dependence of thermoelectric power in both the systems is complex particularly in the composition range between 60 and 80 mol% Tl. The experimental results of the present work are compared with the previous data of liquid telluride systems and are discussed in the light of current transport theories employed in liquid semiconductors.
Monte‐Carlo Study of Two‐Dimensional Antiferromagnets with Competing Anisotropies
Authors: Aplesnin S. S. 
Published: July 2007

AbstractPhase diagrams of the ground state of the “easy plane” (EP) and “easy axis” (EA) antiferromagnet, the “oblique” phase, and the spin glass are calculated by the Monte‐Carlo method for an antiferromagnet with random distribution of competing anisotropies. The radial distribution function of spins in the plane and along “easy axes” and the correlation radius of EA and EP phases near the critical concentration of the transition are obtained. The phase diagram of the antiferromagnet, the “oblique” AF, and the paramagnet is estimated for the constant of anisotropy (EA) D∥ = J, (EP) D⟂ = −5J in the variables concentration and temperature.
Magnon Spectrum of Two‐Component Amorphous Ferromagnets
Authors: Vakarchuk I. A. , Margolych I. F. 
Published: July 2007

AbstractThe equations for the energy spectrum and damping of magnetic excitations caused by their scattering on structural fluctuations are obtained for a topologically disordered many‐component system of magnetic atoms. The acoustic and optic branches of the spectrum of the two‐component amorphous ferromagnet are calculated explicitely in the quasi‐crystalline approximation. Numerical calculations of the “energy‐momentum” dependence are made for an amorphous ferromagnet with liquid‐like structure.
The Microscopic Approach to the Description of the Optical Activity in Dielectric Crystals
Authors: Kotsur S. S. , Stasyuk I. V. 
Published: July 2007

AbstractVarious aspects of the microscopic description of the natural optical activity of ionic dielectric crystals are discussed. In the presented approach the electron and phonon excitations as well as their interactions are taken into account. The crystalline contributions to the effect and contributions from single ions or ionic groups are separated; they are studied in detail. Formalism of the Hubbard operators and two‐time Green functions method give the possibility to develop the theory of gyrotropy for a wide family of crystals having a complicated structure of the spectrum of active electron levels. Using the mechanical exciton conception the possibility to apply the crystal point symmetry is demonstrated.