Results 1 - 10 of 1129
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[en] We consider the large-angle diffuse scattering of thermal-energy atoms by defects or adsorbates on a surface. We obtain the Debye-Waller factor for the thermal attenuation of the incoherent elastic peak. When the Debye exponent is small, the diffuse inelastic contribution is dominated by the single-phonon exchange, and is proportional to the frequency distribution function of the defect or adsorbate. We discuss its magnitude compared to the multiphonon background
[en] The Lindemann parameters delta, and the root-mean square thermal vibration amplitudes √< Vi2> of 54 metallic elements both at fusion and at room temperatures are calculated through the combination of the Debye-Waller and the Lindemann equations. The magnitude and ratio of the average Lindemann parameters deltasup(r)fsub(i) with i=1,2 and 3 for the fusion transitions; A2→ liquid, A1→ liquid and A3→ liquid, are respectively deltafisup(r)=0.226, = 0.185 and deltafsub(3)sup(r)=0.131. deltafsub(1)sup(r):deltafsub(2)sup(r):deltafsub(3)sup(r)=1:0821:0.578. The hypotheses of Lindemann, Gilvarry and Shapiro on the fusion phenomena due to lattice vibration of metals are justified. The role of lattice structure of fusion is also demonstrated. (author)
[en] Iron microcrystal ranging in size from 70 to 450 A have been investigated by the Moessbauer effect. There is, compared to the bulk value, a small enhancement of the magnetic field at the side of the nucleus of about 1% which can be interpreted as due to the demagnetisation field of the microcrystals and their geometric arrangement. The observed drastic size and temperature dependent lowering of the Debye Waller factor cannot be explained by a change of the Debye temperature of the microcrystals. Two different models are proposed to explain the effect. (orig.)
[de]Mit Hilfe des Moessbauereffekts wurden Eisenmikrokristalle im Groessenbereich zwischen 70 und 450 A untersucht. Im Vergleich zum 'bulk'-Wert findet man eine kleine Zunahme des magnetischen Feldes am Ort des Kerns von etwa 1%, die als Entmagnetisierungsfeld des Mikrokristalls und dessen geometrischer Anordnung interpretiert werden kann. Die beobachtete stark groessen- und temperaturabhaengige Abnahme des Debeye-Waller-Faktors kann nicht mit einer Aenderung der Debye-Temperatur des Mikrokristalls erklaert werden. Zur Erklaerung des Effekts werden zwei verschiedene Modelle vorgeschlagen. (orig.)
[en] We investigate the link between dynamic localization, characterized by the Debye–Waller factor, 〈u2〉, and solute self-diffusivity, D, in a polymer system using atomistic molecular dynamics simulations and vapor sorption experiments. We find a linear relationship between lnD and 1/〈u2〉 over more than four decades of D, encompassing most of the glass formation regime. The observed linearity is consistent with the Langevin dynamics in a periodically varying potential field and may offer a means to rapidly assess diffusion based on the characterization of dynamic localization.
[en] The spatial intensity profile of an X-ray beam reflected by a crystal with microdefects in the Bragg case is considered. A practically pure diffuse component was measured at the tail of the intensity distribution. From these data, static Debye-Waller factors of nearly perfect silicon crystals were obtained. (orig.)
[en] The Debye-Waller factors in graphite for the atomic motions within the basal plane and also across the basal planes have been calculated using the various lattice dynamical models available to date and a critical comparison is made with the existing experimental data from X ray and neutron scattering studies. The present study reveals the need for further investigation on the nature of atomic motion across the basal planes. (author). 15 refs, 1 tab
[en] In present work the dependence of parameters of junction area on composition of top layer of hetero structure Pb1-xSnxTe/PbTe1-ySey prepared by a method molecular-beam-epitaxy was investigated. By the methods of asymptotical Bregg diffractometry have been determined thickness of a junction layer, deformation and static Debye-Waller factor. The calculations are carried out in kinematic approximation, allowed to obtain profile of distribution of deformation and static Debye-Waller factor in these structures
[en] Debye-Waller factors for the As-O-O triangular multiple scattering paths within the arsenate in Na2HAsO4·7H2O are evaluated in terms of magnitude ratio with respect to the Debye-Waller factor of the nearest neighbour As-O shell (σ2As−0−0/σ2As-0). The arsenates are studied under two different levels of distortion from an ideal tetrahedron, i.e. a relatively high distortion in the powder form and a nearly ideal tetrahedron in an aqueous solution at pH 14. The Debye-Waller factor ratio σ2As−0−0/σ2As-0) is found to be 2.0 and 1.9 for the powder and liquid sample, respectively, appearing to be insensitive to the distortion of the arsenate tetrahedron.