Temat: 61.10.Dp - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Experimental Determination of Reflection Phases by Three-Beam Diffraction and its Applications
Autorzy:: Hümmer, K.
Schwegle, W.
Weckert, E.
Tematy:: 61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1920833.pdf Link otwiera się w nowym oknie
Opis:: Information on phase relationships between Bragg reflections can be obtained by the interference of Bragg waves. In the three-beam case, phase difference is given by a structure invariant triplet phase relationship. The intensity variation due to the three-beam interaction can be best measured by a ψ-scan experiment. The resulting ψ-scan diffraction profiles scanning through a three-beam position uniquely depend on the triplet phase relationship involved. In principle each three-beam profile is given by a superposition of a symmetrical phase-independent and a phase-dependent profile. Thus, triplet phases can be determined experimentally with an accuracy of about 45 degrees. The ψ-scan method is discussed and some examples of applications to the determination of the absolute structure as well as to the structure determination by combination of measured triplet phases with direct methods are given.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Resonant Scattering of Light Atoms - Measuring Methods and Applications
Autorzy:: Grochowski, J.
Serda, P.
Tematy:: 35.20.Bm
61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1920844.pdf Link otwiera się w nowym oknie
Opis:: The paper describes measuring methods of weak resonant scattering signals occurring in X-ray diffraction pattern of a crystal containing light atoms (C, N, O, F) in its unit cell. Difficulties resulting from the large distance on the energy scale between the K-absorption edges of light atoms and contemporary available energy range of X-ray sources for diffraction experiments may be overcome using mixed synchrotron radiation and sealed tube measurements. Techniques such as high resolution synchrotron radiation diffraction experiment, low resolution azimuthal scan, top reflection azimuthal scan are discussed and their applications are presented. Several enantiomer correctness indicators, evaluating the confidence level of absolute structure determination, are applied for crystals containing oxygen or nitrogen as anomalous scatterers. Resonant scattering of light atoms, which are fundamental constituents of organic molecules and polymers, carries the information about the absolute structure. Growing importance of stereospecific drugs which follows recent recognition of drug-receptor interaction mechanism increases the demand for determination of drug molecule handedness. Investigation of absolute structure for molecules in their original shape (without the introduction of heavy anomalous scatterers) is potentially a vast application field of the described methodology.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Investigation of Morphology and Chemical Composition of Self-Organized Semiconductor Quantum Dots and Wires by X-Ray Scattering
Autorzy:: Holý, V.
Meduňa, M.
Stangl, J.
Roch, T.
Bauer, G.
Tematy:: 61.10.-i
61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2030767.pdf Link otwiera się w nowym oknie
Opis:: X-ray scattering methods suitable for the investigation of the morphology and chemical composition of self-organized quantum dots and quantum wires are reviewed. Their application is demonstrated in experimental examples showing that a combination of small angle X-ray scattering with high-resolution X-ray diffraction can reveal both the shape and the chemical composition of the self-organized objects.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 4.

Tytuł:: Structure Factor for Quasicrystals - 1D Case
Autorzy:: Kozakowski, B.
Wolny, J.
Tematy:: 61.44.Br
61.43.-j
61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2036878.pdf Link otwiera się w nowym oknie
Opis:: Using a statistical approach a simple formula for the structure factor of decorated Fibonacci chain was derived. Although the used method operates in the physical space only, its equivalence to the higher-dimensional analysis was proved. Applications of the analysis to different decorated structures were also discussed.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: On the Critical Points of the Structure Amplitude for the Case of One-Dimensional Displacive Modulation
Autorzy:: Śliwińska, T.
Gusin, P.
Warczewski, J.
Tematy:: 61.44.Fw
61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2043371.pdf Link otwiera się w nowym oknie
Opis:: The behavior of the structure amplitude is analyzed in terms of the harmonics of a modulation function for the case of one-dimensional longitudinal displacive modulation. This modulation function is given by a finite series of N sine functions. It turns out that: (1) for the large values of the amplitudes of the modulation function the structure amplitude tends to zero for the arbitrary values of the order m of the satellite reflections; (2) for certain values of the amplitudes of the modulation function the modulus of the structure amplitude assumes its maximum value and (3) for the latter case the intensity of an arbitrary satellite reflection is a function of the intensities of both the closest main reflection and the intensities of the finite set of the neighbor satellite reflections.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 6.

Tytuł:: X-Ray Optics for Synchrotron Radiation
Autorzy:: Malgrange, C.
Tematy:: 61.10.Dp
78.90.+t; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1920813.pdf Link otwiera się w nowym oknie
Opis:: This paper presents the main optical devices used to prepare a beam from X-ray synchrotron source: monochromators, flat or curved in order to intercept a larger angular divergence at the sample, mirrors and, finally, optics for polarized X-ray experiments. Since X-ray optics is based either on total reflection or on diffraction by perfect crystals, the basic fundamental results of X-ray dynamical theory, which are necessary to understand the reasons why one device should be chosen rather than the other, are also presented.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Influence of Interfacial Effects on X-ray Diffraction Spectra of the [GaAs]$\text{}_{n}$[AlAs]$\text{}_{m}$ Superlattices
Autorzy:: Gładyszewski, Grzegorz
Tematy:: 61.10.Dp
68.65.+g; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1879928.pdf Link otwiera się w nowym oknie
Opis:: Influence of interdiffusion, terrace growth, and macroscopic uniformity on X-ray diffraction spectra of [GaAs]$\text{}_{n}$[A1As]$\text{}_{m}$ superlattices are presented. High-angle spectra are analysed on the basis of the kinematic theory of diffraction, whereas low-angle spectra are analysed using the dynamic theory. Computer--simulated (using a Monte-Carlo method) spectra based on a "statistical" model of the superlattice structure are applied in the analysis.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 8.

Tytuł:: Surface Roughness by X-ray and Neutron Scattering Methods
Autorzy:: Sinha, S. K.
Tematy:: 61.10.Dp
68.35.Bs
78.20.Ci; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1945176.pdf Link otwiera się w nowym oknie
Opis:: We discuss how the roughness and morphology of surfaces and interfaces can be characterized by the nondestructive techniques of X-ray and neutron scattering. We first discuss the mathematical description of rough surfaces in terms of correlation functions and then discuss the various kinds of rough surfaces which exist. These fall into the category of self-affine (Gaussian) surfaces, surfaces with capillary wave fluctuations, stepped surfaces, and surfaces with islands or pits. We then discuss how the scattering from such surfaces may be described and which types of information are available from specular reflectivity, off-specular (diffuse) scattering, and grazing incidence reflection experiments, including a comparison with results obtained by other surface techniques. We then discuss multiple rough interfaces and the scattering from thin films and multilayers. Finally, we shall discuss scattering of neutrons by magnetically rough surfaces and multilayers.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 9.

Tytuł:: Magnetic X-Ray Scattering
Autorzy:: Vettier, C.
Tematy:: 75.25.+z
75.40.-s
61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/1931650.pdf Link otwiera się w nowym oknie
Opis:: It was proposed in the 1950's that X-rays could be used to probe magnetization densities. After some experimental demonstrations of the technique, applications have shown that the use of magnetic X-ray scattering combined with synchrotron radiation can lead to important new discoveries in the magnetism of solid materials. Several important features have emerged, especially the resonant magnetic X-ray scattering: large enhancements of scattered intensities, site and species selectivity, X-ray energy and polarization dependence. These properties make it possible to study new phenomena: details of magnetic structures of materials including micro-crystals, new aspects of magnetic phase transitions and surface magnetism.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 10.

Tytuł:: On the Extinction Paradox
Autorzy:: Żakowicz, W.
Tematy:: 32.80.Cy
42.25.Fx
61.10.Dp; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Fizyki PAN
Powiązania:: https://bibliotekanauki.pl/articles/2030470.pdf Link otwiera się w nowym oknie
Opis:: The extinction paradox, the difference of classical and quantum scattering cross-sections for the scattering of particles by a rigid sphere (σ$\text{}^{Q}$=2π a$\text{}^{2}$=2σ$\text{}^{C}$ for ka ≫ 1), is analyzed in a simpler 2D model of a rigid cylindrical potential. Rigorous solutions of the Schrödinger equation for particle beams, including also finite width beams, are derived and employed in the description of the scattering process. The scattering particle fluxes, with a thorough treatment of the forward directions, are being studied. It is pointed out that for wide beams (w ≫ a) the scattered flux can reach the value determined by the quantum theory, provided that it is measured at distances R ≫ waλ. Moderately narrow beams (1≪ w≪ a) behave as classical trajectories, and their scattering can be described in classical terms. Thus, the classical limit of quantum scattering requires not only that the de Broglie wavelength λ$\text{}_{B}$ is much smaller than the size of the scatterer (a ≫ λ$\text{}_{B}$), but also that the transverse width of beams of de Broglie's waves is small, w≪ a.
Dostawca treści:: Biblioteka Nauki

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