Showing papers on "Debye published in 1992"
Book•
01 Jan 1992TL;DR: In this article, critical effects in semiclassical scattering have been studied and applications to atomic, nuclear and particle physics applications have been discussed, including near-critical scattering, the theory of the rainbow, the glory and the Debye expansion.
Abstract: 1. Critical effects in semiclassical scattering 2. Diffraction and coronae 3. The rainbow 4. The glory 5. Mie solution and resonances 6. Complex angular momentum 7. Scattering by an impenetrable sphere 8. Diffraction as tunnelling 9. The Debye expansion 10. Theory of the rainbow 11. Theory of the glory 12. Near-critical scattering 13. Average cross sections 14. Orbiting and resonances 15. Macroscopic applications 16. Applications to atomic, nuclear and particle physics References Index.
215 citations
01 Jul 1992
TL;DR: In this paper, critical effects in semiclassical scattering have been studied and applications to atomic, nuclear and particle physics applications have been discussed, including near-critical scattering, the theory of the rainbow, the glory and the Debye expansion.
Abstract: 1. Critical effects in semiclassical scattering 2. Diffraction and coronae 3. The rainbow 4. The glory 5. Mie solution and resonances 6. Complex angular momentum 7. Scattering by an impenetrable sphere 8. Diffraction as tunnelling 9. The Debye expansion 10. Theory of the rainbow 11. Theory of the glory 12. Near-critical scattering 13. Average cross sections 14. Orbiting and resonances 15. Macroscopic applications 16. Applications to atomic, nuclear and particle physics References Index.
198 citations
TL;DR: In this article, the contribution of complex rays and the secondary radiation shed by surface waves to scattering by a dielectric sphere are calculated in the context of the Debye series expansion of the Mie scattering amplitudes.
Abstract: The contributions of complex rays and the secondary radiation shed by surface waves to scattering by a dielectric sphere are calculated in the context of the Debye series expansion of the Mie scattering amplitudes. Also, the contributions of geometrical rays are reviewed and compared with the Debye series. Interference effects between surface waves, complex waves, and geometrical waves are calculated, and the possibility of observing these interference effects is discussed. Experimental data supporting the observation of a surface wave-geometrical pattern is presented.
163 citations
TL;DR: In this paper, the effects of charged clay platelets on the frequency dependent electrical properties of shaly materials are analyzed using simplified models for the membrane polarization around charged spheres immersed in electrolytic solutions, under a thin double layer approximation.
Abstract: The effects of charged clay platelets on the frequency dependent electrical properties of shaly materials are analyzed using simplified models for the membrane polarization around charged spheres immersed in electrolytic solutions, under a thin double layer approximation. The polarization is defined through two possible mechanisms: (1) a surface conductivity related with a modified Stern double layer model (S-model) according to Schurr-Schwarz theory; (2) a coupled electro-diffusional mechanism occurring in a Guoy-Chapman double layer using Fixman's approach (D-model). By comparing the electric potential in such microscopic models with the external potentials derived for the equivalent homogeneous sphere using a Maxwell-Wagner approach, we obtain the total current conductivity functions for these two models. The theory, therefore, provides explicit expressions relating the total conductivity functions to the model parameters.The behavior of the S-model is described by a complex conductivity exhibiting a simple Debye characteristic. In the D-model, both the conductivity and the dielectric permittivity are given as complex properties, showing similar but much wider dispersion than that of a Debye substance. Our representation of the grains and their associated ionic double layers by an equivalent sphere with effective properties allows us to extend our results to simulate rocks containing clays. This is accomplished using generalized mixture equations written in terms of the total conductivity functions. The frequency behavior of both models are compared and their fit to experimental data on clay-water systems and shaly materials suggest that the D-model is more appropriate for representing the dielectric behavior of clay bearing rocks. The theory can be adapted to estimate the clay parameters of a shaly sandstone using electromagnetic borehole measurements.
152 citations
TL;DR: The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques and suggests the existence of a second conductance mechanism.
Abstract: The Kapitza conductance between isotopically enriched synthetic diamond and Ti, Al, Au, and Pb has been studied using picosecond optical techniques. For Ti and Al, which have Debye temperatures roughly 1/5 of that of diamond, the measured heat flow is in reasonable agreement with calculations of the phonon heat transport based on a simple lattice dynamical model. However, for Au and Pb, which have Debye temperatures 0.07 and 0.04 times that of diamond, the measured Kapitza conductances are as much as 100 times larger than expected, suggesting the existence of a second conductance mechanism.
126 citations
TL;DR: The use of F.J. Olver's (1974) uniform asymptotic expansions to compute Hankel functions (of interest in EM scattering) of complex argument z and complex order v is examined in this paper.
Abstract: The use of F.W.J. Olver's (1974) uniform asymptotic expansions to compute Hankel functions (of interest in EM scattering) of complex argument z and complex order v is examined. Emphasis is placed on how to choose the proper branches in evaluation of the complex functions in the asymptotic representations. Comparison is made with the nonuniform formulas of Debye and Watson. The Debye formulas are valid when z and v are far apart, and the Watson formulas are valid when z and v are close together. The fact that the Olver formulas are uniform is important from a numerical viewpoint, because a satisfactory criterion for deciding when to switch between the Debye and Watson (1958) formulas is not available. Validation by comparison with two nonasymptotic methods verifies that the Olver formulas are considerably more accurate than the Debye or Watson formulas. >
91 citations
TL;DR: An analysis incorporating both vibrational and strongly coupled rotational degrees of freedom expected for the simple-cubic structure at low temperatures is proposed and a possible interpretation based on a fairly narrow feature in the excitation spectrum is discussed.
Abstract: We have measured a large specific heat of polycrystalline ${\mathrm{C}}_{60}$ from T=14 to 20 K The data were adequately fitted by a model containing Debye terms, Einstein oscillators, and a linear contribution An analysis incorporating both vibrational and strongly coupled rotational degrees of freedom expected for the simple-cubic structure at low temperatures is proposed We also discuss a possible interpretation based on a fairly narrow feature in the excitation spectrum The large linear term may be a consequence of disorder resulting in a distribution of two-level tunneling centers
85 citations
TL;DR: Using molecular-dynamics computer simulation, the dynamical behavior of the isotropic and nematic phases of highly anisotropic molecular fluids is studied and the Debye diffusion model appears to explain the reorientational mechanism in the nematic phase.
Abstract: Using molecular-dynamics computer simulation, we study the dynamical behavior of the isotropic and nematic phases of highly anisotropic molecular fluids. The interactions are modeled by means of the Gay-Berne potential with anisotropy parameters \ensuremath{\kappa}=3 and \ensuremath{\kappa}'=5. The linear-velocity autocorrelation function shows no evidence of a negative region in the isotropic phase, even at the higher densities considered. The self-diffusion coefficient parallel to the molecular axis shows an anomalous increase with density as the system enters the nematic region. This enhancement in parallel diffusion is also observed in the isotropic side of the transition as a precursor effect. The molecular reorientation is discussed in the light of different theoretical models. The Debye diffusion model appears to explain the reorientational mechanism in the nematic phase. None of the models gives a satisfactory account of the reorientation process in the isotropic phase.
72 citations
TL;DR: This work uses numerical simulations to study the spatial structure of a quark and an antiquark in the imaginary-time excitations which mediate the Debye screening of color singlet sources in the high-temperature phase of QCD and finds that these correlation functions are very similar to the zero-tem temperature wave functions of the corresponding particles.
Abstract: We use numerical simulations to study the spatial structure of a quark and an antiquark in the imaginary-time excitations which mediate the Debye screening of color singlet sources in the high-temperature phase of QCD. We find that these correlation functions are very similar to the zero-temperature wave functions of the corresponding particles. This result contrasts with results on the \ensuremath{\rho} and nucleon screening lengths for these sources, which are well described by a gas of free or weakly interacting quarks.
56 citations
TL;DR: In this article, it was shown that Debye screening of gauge charges during the electroweak phase transition does not affect the charge transport mechanism for anomalous electroweak baryogenesis.
37 citations
TL;DR: In this paper, the main features of the distribution of activation energies, G (E ), for some empirical functions frequently used to describe this behavior, such as the Havriliak-Negami and the Williams-Watts functions, are analyzed and compared with the double-exponential G(E ) obtained from the ion-hopping model.
TL;DR: In this paper, the general solutions for the coupled diffusion-reaction equations describing reversible electron transfer reactions in Debye solvents, governed by Sumi-Marcus free energy surfaces, are extended to non-Debye and non−Debye solVents.
Abstract: The general solutions obtained earlier [J. Chem. Phys. 95, 3325 (1991)] for the coupled diffusion‐reaction equations describing reversible electron transfer reactions in Debye solvents, governed by Sumi–Marcus free energy surfaces, are extended to non‐Debye solvents. These solutions, which depend on the time correlation function of the reaction coordinate Δ(t), are exact in the narrow and wide window limits for Debye and non‐Debye solvents and also in the slow reaction and non‐diffusion limits for Debye solvents. The general solution also predicts the behavior between these limits and can be obtained as the solution to an integral equation. An iterative method of solving this equation using an effective relaxation time is discussed. The relationship between Δ(t) and the time correlation function S(t) of Born solvation energy of the reacting intermediates is elucidated.
TL;DR: In this article, expressions for the time dependence of the longitudinal relaxation parameter for solvents exhibiting two and three Debye relaxation processes are developed on the basis of the model of Hynes.
TL;DR: In this paper, the corrections to the transport cross-sections and collision integrals for Coulomb interactions arising from the application of realistic interaction energies of the ions of nitrogen and oxygen are investigated.
Abstract: The corrections to the transport cross-sections and collision integrals for Coulomb interactions arising from the application of realistic interaction energies of the ions of nitrogen and oxygen are investigated. Accurate potential-energy curves from an ab initio electronic-structure calculation and a semiclassical description of the scattering are used to determine the difference between the cross-sections for the real interaction forces and a Coulomb force for large values of the Debye shielding parameter. Graphs of the correction to the diffusion and viscosity-collision integrals are presented for temperatures from about 10,000 K to 150,000 K. This correction can be combined with tabulations of the collision integrals for shielded Coulomb potentials to determine the contribution of N(+)-N(+), N(+)-O(+), and O(+)-O(+) interactions to the transport properties of high-temperature air. Analytical forms are fitted to the calculated results to assist this application.
TL;DR: In this paper, a study of fluctuation effects in the resistance R, and the thermoelectric power S, of melt-processed BiSrCaCuO (2212) and sintered BiPbSrCACuO(2223) polycrystalline materials is presented.
Abstract: The authors report a study of fluctuation effects in the resistance R, and the thermoelectric power S, of melt-processed BiSrCaCuO (2212) and sintered BiPbSrCaCuO (2223) polycrystalline materials. Applying several theoretical models to the analysis of experimental results, they extract a number of physical parameters for these systems: the Fermi energy, interlayer coupling strength and atomic Debye temperatures for Bi and Pb. The results are in good agreement with data obtained in other studies of similar materials.
TL;DR: In this article, the reflection and refraction of harmonic heterogeneous waves by a plane, isotropic viscoelastic layer are described in the framework of linear acoustics, and the energy balance is also established.
TL;DR: The equations for the spin-$\frac{3}{2}$ perturbations of a rotating charged black hole given by the linearized O(2) extended supergravity model are solved, expressing their complete solution in terms of two Debye potentials that obey the same differential equation.
Abstract: The equations for the spin-$\frac{3}{2}$ perturbations of a rotating charged black hole given by the linearized O(2) extended supergravity model are solved, expressing their complete solution in terms of two Debye potentials that obey the same differential equation. The equation governing the radial parts of the Debye potentials is transformed into a Schr\"odinger-type equation with a short-range real potential. It is also shown that there exist spin-$\frac{3}{2}$ perturbations corresponding only to ingoing or only to outgoing waves.
TL;DR: In this article, the absolute values of longitudinal and transversal sound velocities in ceramic samples of Bi2Sr2Can-1CunO2n+4 (n=1, 2,3) were measured.
Abstract: We have measured the absolute values of longitudinal and transversal sound velocities in ceramic samples of Bi2Sr2Can-1CunO2n+4 (n=1, 2,3). We have compared various methods of calculation of "true" elastic moduli of matrix material. We used best of them to find the elastic moduli, sound velocities and Debye temperatures of the material. The calculated elastic moduli are low in a comparison with other oxide superconductors. The velocities and Debye temperatures increase with increasing n.
TL;DR: In this article, acoustic and optical Debye temperatures are calculated and correlated for rare earth tellurite glass systems, and the Debye temperature ΘD derived in this way characterizes the total vibrational spectrum in that optical and acoustic modes are separated.
Abstract: Acoustic and optical Debye temperatures are calculated and correlated for rare earth tellurite glass systems. The binary tellurite vitreous systems can be represented by the general formula [TeO2]0.9 [AnOm]0.1, (A - La, Ce, and Sm). The acoustic Debye temperature data are obtained from ultrasonic velocity (longitudinal and shear) measurements. The optical Debye temperatures are calculated from infrared absorption spectra. The Debye temperature ΘD derived in this way characterizes the total vibrational spectrum in that optical and acoustic modes are separated.
Akustische und optische Debye-T emperaturen fur Seltenerd-T ellurit-G lassysteme werden berechnet und verglichen. Die binaren Tellurit-G lassysteme konnen mit der Formel [TeO2]0,9 [AnOm]0,1 (A - La, Ce, Sm) beschrieben werden. Die akustischen Debye-T emperaturen werden durch Messungen der (longitudinalen und Scher-) Ultraschallgeschwindigkeit erhalten. Die optischen Debye-T emperaturen werden aus den IR-A bsorptionsspektren berechnet. Die so abgeleitete Debye-T emperatur ΘD charakterisiert das gesamte Schwingungsspektrum, in dem optische und akustische Moden getrennt sind.
15 Jun 1992
TL;DR: In this article, an exact analytical solution for T e = T i and an approximate solution for t e ≠ T i have been obtained for the unidimensional non-linear Debye potential, which is a solution of the Poisson equation obtained by expanding up to third order Boltzmann's factors.
Abstract: An exact analytical solution for T e = T i and an approximate solution for T e ≠ T i have been obtained for the unidimensional non-linear Debye potential. The approximate expression is a solution of the Poisson equation obtained by expanding up to third order the Boltzmann's factors. The analysis shows that the effective Debye screening length can be quite different from the usual Debye length, when the potential to thermal energy ratio of the particles is not much smaller than unity.
TL;DR: In this paper, a neutron powder diffraction study of four PdDx materials: palladium metal, α-PdDDx and two samples of β-pdD0.6 was performed.
TL;DR: In this article, a new torsion pendulum, with continuously variable moment of inertia, was presented, which allows measurements of the partial derivative of the internal friction and the oscillation frequency with respect to the moments of inertia at constant temperature.
Abstract: The internal friction (loss tangent) of solids is normally measured, as a function of temperature, with a torsion pendulum operating in free decay. Curves of the internal friction and the oscillation frequency, against temperature, are obtained at various moments of inertia, to extract the parameters characteristic of the relaxation process (relaxation time and strength). In all these experiments only the temperature is considered as an independent variable and the moment of inertia of the pendulum is mainly used to shift the internal friction peaks in the temperature scale. It is pointed out in the paper that the moment of inertia is also an independent variable which can be used to determine, with high accuracy, if the measured peak is of the Debye type or not. A new torsion pendulum, with continuously variable moment of inertia is presented, which allows measurements of the partial derivative of the internal friction and the oscillation frequency with respect to the moment of inertia, at constant temperature. Finally, some measurements of the Snoek relaxation in Nb-O alloys are presented, to show the applicability of the concepts developed in the paper.
TL;DR: In this paper, the authors applied the equation of motion method for the Green's functions to study the behaviour of pairs of interacting two-level tunnelling units coupled with a phonon field to calculate, within the framework of the small-polaron theory, the dynamic susceptibilities and relaxation rates of the system.
Abstract: The equation of motion method for the Green's functions is applied to study the behaviour of pairs of interacting two-level tunnelling units, coupled with a phonon field to calculate, within the framework of the small-polaron theory, the dynamic susceptibilities and relaxation rates of the system. Explicit expressions for these quantities are obtained in the Debye approximation.
TL;DR: In this article, the pure translational absorption spectrum of hydrogen gas has been measured from 20 to 100 cm −1 at temperatures in the range 24-37 K. Superposed on the broad translational band is the sharp rotational line R(0) of HD, present in the gas in natural abundance.
Abstract: The pure translational absorption spectrum of hydrogen gas has been measured from 20 to 100 cm −1 at temperatures in the range 24-37 K. Superposed on the broad translational band is the sharp rotational line R(0) of HD, present in the gas in natural abundance. From the intensity of the line, the electric dipole moment is determined to be (0.81 ± 0.05) × 10 -3 debye. The measurements are of relevance to the infrared opacity and to the D/H ratio of the atmospheres of the giant planets
Patent•
08 Sep 1992
TL;DR: In this article, an electric field is applied on a film consisting of a polymer containing a compd. having functional group parts with >= 1 debye dipole moment, and it is preferable that the compd has both of electron-donating groups and electron-withdrawing groups.
Abstract: PURPOSE:To obtain a double refraction film at low cost with a simple process which can improve coloring and characteristics of view angle of a liquid crystal display device by using a compd. having specified functional groups to form the double refraction film. CONSTITUTION:An electric field is applied on a film consisting of a polymer containing a compd. having functional group parts with >=1 debye dipole moment. The obtd. double refraction film has such refraction index characteristics that the refractive index in the thickness direction is larger than one of two principal refractive indices in the film plane. Functional groups having >=1 debye dipole moment is, for example, a compd. having electron- donating groups or electron-withdrawing groups as substitutents in a benzene ring. It is preferable that the compd. has both of electron-donating groups and electron-withdrawing groups, and has 3.0 or more debye dipole moment.
TL;DR: In this paper, Compton and Debye's kinematic relations are obtained within the realm of a completely classical theory, that is, without having to consider the wave-particle duality for the molecules or the radiation.
Abstract: Einstein and Ehrenfest's radiation theory is modified in order to take into account the effects of the random zero-point fields, characteristic of classical stochastic electrodynamics, in a system of classical molecules interacting with thermal radiation. This is done by replacing the Einstein concept of “random spontaneous emission” by the concept of stimulated emission by the random zero-point fields. As a result, Compton and Debye's kinematic relations are obtained within the realm of a completely classical theory, that is, without having to consider the wave-particle duality for the molecules or the radiation.
TL;DR: In this article, a new method of diffraction pattern calculation on quasicrystals is proposed and tested using the Debye-Waller approximation, which is well approximated by a rapidly convergent series expansion of a variable u that describes nearest distances between atomic positions and points of the reference lattice.
Abstract: A new method of diffraction-pattern calculation is proposed and tested on quasicrystals. With use of an appropriately defined reference lattice, a structure factor can be well approximated by a rapidly convergent series expansion of a variable u that describes nearest distances between atomic positions and points of the reference lattice. Only the first few terms are significant for difffraction-pattern calculation. The possibility of using the Debye–Waller approximation is discussed. In this case an appropriate shift of the reference structure is required. Calculations based on the Debye–Waller formula in real and phason spaces give similar results.
TL;DR: In this article, a generalized van Cittert-Zernike theorem was proposed to describe the spatial coherence of wave fields with respect to the source radiance in a generalized quasihomogeneous wave model.
Abstract: The analogy between the van Cittert-Zernike theorem and diffraction in focal regions is discussed. For wavefields that can be approximated by a generalized quasihomogeneous wave model, the spatial coherence is described by a generalized van Cittert-Zernike theorem even close to the source. The main difference between the classical and the generalized theorem is that the source intensity in the former is replaced by the source radiance in the direction of the observation point in the latter. The spatial coherence is related to the source radiance by a modified Debye integral, which implies that the wave energy is propagated according to the laws of classical radiometry. No assumption of source incoherence is involved, and the results apply to radiation from both primary sources and secondary sources like rough scattering objects or illuminated apertures in optical systems.
Journal Article•
TL;DR: In this article, the temperature dependence of the absorption areas and isomer shifts were fitted to equations derived from the Debye model of solids with appropriate approximations to the relevant Debye integrals.
Abstract: 57 Fe Mossbauer spectra of phosphate glasses containing iron obtained over a temperature range 12-600 K consisted of two broadened quadrupole doublets characteristic of octahedral Fe 3+ and Fe 2+ sites. No compositional trends could be discerned. The temperature dependence of the absorption areas and isomer shifts were fitted to equations derived from the Debye model of solids with appropriate approximations to the relevant Debye integrals
TL;DR: In this paper, it is observed that the case of glass formation increases with the molecular asymmetry of the liquid and this results in a lesser T m /T g ratio, where T n and T g are the melting -and glass transition-temperatures respectively.