The X-ray standing wave (XSW) technique is an X-ray interferometric method combining diffraction with a multitude of spectroscopic techniques. It is extremely powerful for obtaining information about ...virtually all properties of surfaces and interfaces on the atomic scale. However, as with any other technique, it has strengths and limitations. The proper use and necessary understanding of this method requires knowledge in quite different fields of physics and technology. This volume presents comprehensively the theoretical background, technical requirements and distinguished experimental highlights of the technique. Containing contributions from the most prominent experts of the technique, such as Andre Authier, Boris Batterman, Michael J Bedzyk, Jene Golovchenko, Victor Kohn, Michail Kovalchuk, Gerhard Materlik and D Phil Woodruff, the book equips scientists with all the necessary information and knowledge to understand and use the XSW technique in practically all applications.Sample Chapter(s)Chapter 1: X-Ray Standing Waves in a Nutshell (536 KB)Contents:Part I:X-Ray Standing Waves in a Nutshell (Jörg Zegenhagen and Alexander Kazimirov)Dynamical Theory of X-Ray Standing Waves in Perfect Crystals (André Authier)X-Ray Standing Wave in Complex Crystal Structures (Victor Kohn)X-Ray Standing Wave in a Backscattering Geometry (D P Woodruff)X-Ray Standing Wave at the Total Reflection Condition (Michael J Bedzyk)X-Ray Standing Wave at Grazing Incidence and Exit (Osami Sakata and Terrence Jach)X-Ray Standing Wave in Multilayers (Michael J Bedzyk and Joseph A Libera)Kinematical X-Ray Standing Waves (Martin Tolkiehn and Dmitri V Novikov)X-Ray Waveguides (Ianna Bukreev, Alessia Cedola, Daniele Pellicia, Werner Jark and Stefano Lagomarsino)Compton Scattering from X-Ray Standing Wave Field (Vladimir Bushuev)Theory of Photoelectron Emission from an X-Ray Interference Field (Ivan A Vartanyants and Jörg Zegenhagen)Site-Specific X-Ray Photoelectron Spectroscopy Using X-Ray Standing Waves (Joseph C Woicik)Experimental Basics (Alexander Kazimirov and Jörg Zegenhagen)Part II::XSW Imaging (Michael J Bedzyk and Paul Fenter)X-Ray Standing Waves in Quasicrystals: Atomic Positions in an Aperiodic Lattice (Terrence Jach)X-Ray Standing Waves in Thin Crystals: Probing the Polarity of Thin Epitaxial Films (Alexander Kazimirov, Jörg Zegenhagen, Tien-Lin Lee and Michael Bedzyk)Isotopic Effect on the Lattice Constant of Germanium and Silicon (Alexander Kazimirov, Jörg Zegenhagen, Evgeny Sozontov, Victor Kohn and Manuel Cardona)Biomembrane Models and Organic Monolayers on Liquid and Solid Surfaces (S I Zheludeva, N N Novikova, M V Kovalchuk, N D Stepina, E A Yurieva, E YU Tereschenko and O V Konovalov)Applications of XSW in Interfacial Geochemistry (Paul Fenter)Complex Surface Phases of Sb on Si(113): Combining XSW and Density Functional Theory (M Siebert, Th Schmidt, J I Flege and J Falta)X-Ray Standing Wave Analysis of Non-Commensurate Adsorbate Structures Produced by Ga Adsorption on Ge(111) (Jörg Zegenhagen)Photon Stimulated Desorption (Jan Ingo Flege, Thomas Schmidt, Jens Falta, Alexander Hille and Gerhard Materlik)Depth-Profiling of Marker Layers Using X-Ray Waveguides (Ajay Gupta)Coherent Diffraction Imaging with Hard X-Ray Waveguides (Liberato de Caro and Cinzia Giannini, Daniele Pelliccia, Alessia Cedola and Stefano Lagomarsino)X-Ray Standing Wave for Chemical-State Specific Surface Structure Determination (D P Woodruff)Site-Specific X-Ray Photoelectron Spectra of Transition-Metal Oxides (Joseph C Woicik)Probing Multilayer Nanostructures with Photoelectron and X-Ray Emission Spectroscopies Excited by X-Ray Standing Waves (S-H Yang, B C Sell, B S Mun and C S Fadley)Readership: Academics, graduate students and industry researchers in spectroscopy/other analytical techniques, condensed matter physics/solid state physics, surface/interface chemistry and applied physics; synchrotron laboratory scientists, material scientists, chemists and physicists.
High-throughput crystallography is an important tool in materials research, particularly for the rapid assessment of structure-property relationships. We present a technique for simultaneous ...acquisition of diffraction images and fluorescence spectra on a continuous composition spread thin film using a 60 keV x-ray source. Subsequent noninteractive data processing provides maps of the diffraction profiles, thin film fiber texture, and composition. Even for highly textured films, our diffraction technique provides detection of diffraction from each family of Bragg reflections, which affords direct comparison of the measured profiles with powder patterns of known phases. These techniques are important for high throughput combinatorial studies as they provide structure and composition maps which may be correlated with performance trends within an inorganic library.
Among the various materials suitable for organic thin-film transistors (OTFTs), pentacene stands out as a model molecule, exhibiting one of the highest field effect mobilities reported so far. ...Understanding the growth mechanism of pentacene on dielectrics is essential for controlling film morphology and for fabricating high quality, large-grain, defect-free films. Such films will help us gain insight into the fundamentals of transport in organic films as well as enable the ultimate OTFT performance. In situ synchrotron X-ray scattering was used to probe the early stages of pentacene growth on SiO
2 in real time and under conditions relevant to the fabrication of OTFTs. Reflectivity measurements reveal that a thin layer of water, initially present on the substrate, is trapped at the interface when the pentacene film is deposited. Therefore, the interface relevant for OTFTs is that between pentacene and water. Anti-Bragg oscillations, observed for the first time during organic film growth, reveal that the first monolayer of pentacene completes fully before the second one nucleates. Subsequent layers nucleate before the underlying layers complete, giving rise to the characteristic island structure observed in pentacene films used in OTFTs. A simple distributed growth model was found to adequately describe the growth mechanism.
The X-ray standing wave (XSW) technique is an X-ray interferometric method combining diffraction with a multitude of spectroscopic techniques. It is extremely powerful for obtaining information about ...virtually all properties of surfaces and interfaces on the atomic scale. However, as with any other technique, it has strengths and limitations. The proper use and necessary understanding of this method requires knowledge in quite different fields of physics and technology. This volume presents comprehensively the theoretical background, technical requirements and distinguished experimental highlights of the technique. Containing contributions from the most prominent experts of the technique, such as Andre Authier, Boris Batterman, Michael J Bedzyk, Jene Golovchenko, Victor Kohn, Michail Kovalchuk, Gerhard Materlik and D Phil Woodruff, the book equips scientists with all the necessary information and knowledge to understand and use the XSW technique in practically all applications.
The molecular volume of crystals depends on their isotopic masses. This influence originates from the zero-point motion and the resulting small differences in lattice constants. This effect was ...measured with high precision by using an x-ray standing wave. The standing wave is generated during Bragg reflection and thus is in phase with the planes of the substrate crystal, which is covered with a homoepitaxial film that has a different isotopic composition than the substrate. The positions of the surface planes of the film with respect to the substrate planes are revealed by the photoelectrons excited by the maxima of the standing wave. For germanium-76 on natural germanium(111), a difference in lattice constant of -1.1 × 10$^{-5}$ and -2.5 × 10$^{-5}$ at 300 and 54 kelvin, respectively, was found. The results are in good agreement with theoretical predictions.
Previous studies have established that pentacene films deposited on silicon oxide consist of a substrate-induced "thin-film" phase, with the bulk phase of pentacene detected in thicker films only. We ...show that the bulk phase nucleates as early as the first monolayer, and continues to nucleate as film growth progresses, shadowing the growth of the thin-film phase. Moreover, we find that the transition between the "thin-film" and the bulk phase is not a continuous one, as observed in heteroepitaxial systems, but rather the two phases nucleate and grow independently.
The nucleation of noble metal nanoparticles on oxide surfaces can lead to dramatic enhancements in catalytic activity that are related to the atomic-scale formation of the nanoparticles and ...interfaces. For the case of submonolayer Pt deposited on the 2×1 SrTiO3(001) surface atomic-force microscopy shows the formation of nanoparticles. We use X-ray standing wave (XSW) atomic imaging to show that these nanoparticles are composed of Pt face-centered-cubic nanocrystals with cube-on-cube epitaxy laterally correlated to the substrate unit cell. The phase sensitivity of the XSW allows for a direct measurement of the interface offset between the two unit cells along the c-axis. Different Pt coverages lead to differences in the observed XSW image of the interfacial structure, which is explained by a proposed model based on the Pt–Pt interaction becoming stronger than the Pt–substrate interaction as the global coverage is increased from 0.2 to 0.6 ML.
The material response of polycrystalline materials under cyclic loading is not fully understood. Even during uniaxial loading, individual grains embedded within the polycrystalline material can ...experience complicated strain histories. By quantifying the deformation state at the crystal level, we can begin to understand the conditions that lead to fatigue failure. An in situ powder diffraction method was developed and employed at the Cornell High Energy Synchrotron Source to measure the aggregate crystal response at various points in a material's life using synchrotron x ray. A set of experiments was conducted using a load frame capable of exerting cyclic uniaxial loads on a specimen. A high speed x-ray shutter was developed to synchronize the x-ray beam and the loading cycle. Using the high speed shutter, the evolution of the lattice strains for the families of crystallographic planes was measured while the aggregate was under cyclic uniaxial loading, thus monitoring a live evolution of lattice strain in a cyclically loaded specimen. The methodology is demonstrated using uniaxial cyclic specimens machined from oxygen free conductivity (OFHC) copper sheet.
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