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GISAXS
Grazing-incidence small-angle scattering (GISAS) is a scattering technique used to study nanostructured surfaces and thin films. The scattered probe is either photons (grazing-incidence small-angle X-ray scattering, GISAXS) or neutrons (grazing-incidence small-angle neutron scattering, GISANS). GISAS combines the accessible length scales of small-angle scattering (SAS: SAXS or Small-angle neutron scattering, SANS) and the surface sensitivity of grazing incidence diffraction (GID). Applications A typical application of GISAS is the characterisation of self-assembly and self-organization on the Nanoscopic scale, nanoscale in thin films. Systems studied by GISAS include quantum dot arrays, growth instabilities formed during in-situ growth, self-organized nanostructures in thin films of block copolymers, silica mesophases, and nanoparticles. GISAXS was introduced by Levine and Cohen to study the dewetting of gold deposited on a glass surface. The technique was further developed by Na ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grazing Incidence Diffraction
Grazing incidence X-ray and neutron diffraction (GID, GIXD, GIND), typically from a crystalline structure uses small incident angles for the incoming X-ray or neutron beam, so that diffraction can be made surface sensitive. It is used to study surfaces and layers because wave penetration is limited. Distances are in the order of nanometres. Below (typically 80%) the critical angle of the surface material studied an evanescent wave is established for a short distance and is exponentially damped. Therefore, Bragg reflections are only coming from the surface structure. An advantage of GIXD is that the electric field at the critical angle is amplified locally by a factor of four, making the signal stronger. A disadvantage is the limited in-plane spatial resolution (beam footprint). When very small scattering angles are being studied, the technique is called grazing-incidence small-angle scattering (GISAS, GISAXS, GISANS), and requires special methodology. History Before synchrotron ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Synchrotron Light Sources
A synchrotron light source is a source of electromagnetic radiation (EM) usually produced by a storage ring, for scientific and technical purposes. First observed in synchrotrons, synchrotron light is now produced by storage rings and other specialized particle accelerators, typically accelerating electrons. Once the high-energy electron beam has been generated, it is directed into auxiliary components such as bending magnets and insertion devices (undulators or wigglers) in storage rings and free electron lasers. These supply the strong magnetic fields perpendicular to the beam which are needed to convert high energy electrons into photons. The major applications of synchrotron light are in condensed matter physics, materials science, biology and medicine. A large fraction of experiments using synchrotron light involve probing the structure of matter from the sub-nanometer level of electronic structure to the micrometer and millimeter level important in medical imaging. An ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Small-angle Scattering
Small-angle scattering (SAS) is a scattering technique based on deflection of collimated radiation away from the straight trajectory after it interacts with structures that are much larger than the wavelength of the radiation. The deflection is small (0.1-10°) hence the name ''small-angle''. SAS techniques can give information about the size, shape and orientation of structures in a sample. SAS is a powerful technique for investigating large-scale structures from 10 Å up to thousands and even several tens of thousands of angstroms. The most important feature of the SAS method is its potential for analyzing the inner structure of disordered systems, and frequently the application of this method is a unique way to obtain direct structural information on systems with random arrangement of density inhomogeneities in such large-scales. Currently, the SAS technique, with its well-developed experimental and theoretical procedures and wide range of studied objects, is a self-contained ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distorted Wave Born Approximation
Generally in scattering theory and in particular in quantum mechanics, the Born approximation consists of taking the incident field in place of the total field as the driving field at each point in the scatterer. The Born approximation is named after Max Born who proposed this approximation in early days of quantum theory development. It is the perturbation method applied to scattering by an extended body. It is accurate if the scattered field is small compared to the incident field on the scatterer. For example, the scattering of radio waves by a light styrofoam column can be approximated by assuming that each part of the plastic is polarized by the same electric field that would be present at that point without the column, and then calculating the scattering as a radiation integral over that polarization distribution. Born approximation to the Lippmann–Schwinger equation The Lippmann–Schwinger equation for the scattering state \vert\rangle with a momentum p and out-goi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X-rays
X-rays (or rarely, ''X-radiation'') are a form of high-energy electromagnetic radiation. In many languages, it is referred to as Röntgen radiation, after the German scientist Wilhelm Conrad Röntgen, who discovered it in 1895 and named it ''X-radiation'' to signify an unknown type of radiation.Novelline, Robert (1997). ''Squire's Fundamentals of Radiology''. Harvard University Press. 5th edition. . X-ray wavelengths are shorter than those of ultraviolet rays and longer than those of gamma rays. There is no universally accepted, strict definition of the bounds of the X-ray band. Roughly, X-rays have a wavelength ranging from 10 nanometers to 10 picometers, corresponding to frequencies in the range of 30 petahertz to 30 exahertz ( to ) and photon energies in the range of 100 eV to 100 keV, respectively. X-rays can penetrate many solid substances such as construction materials and living tissue, so X-ray radiography is widely used in medic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LBNL
Lawrence Berkeley National Laboratory (LBNL), commonly referred to as the Berkeley Lab, is a United States national laboratory that is owned by, and conducts scientific research on behalf of, the United States Department of Energy. Located in the hills of Berkeley, California, the lab overlooks the campus of the University of California, Berkeley, and is managed by the University of California system. History 1931–1941 The laboratory was founded on August 26, 1931, by Ernest Lawrence, as the Radiation Laboratory of the University of California, Berkeley, associated with the Physics Department. It centered physics research around his new instrument, the cyclotron, a type of particle accelerator for which he was awarded the Nobel Prize in Physics in 1939. Throughout the 1930s, Lawrence pushed to create larger and larger machines for physics research, courting private philanthropists for funding. He was the first to develop a large team to build big projects to make discoverie ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Reflectometer
Neutron reflectometry is a neutron diffraction technique for measuring the structure of thin films, similar to the often complementary techniques of X-ray reflectivity and ellipsometry. The technique provides valuable information over a wide variety of scientific and technological applications including chemical aggregation, polymer and surfactant adsorption, structure of thin film magnetic systems, biological membranes, etc. History Neutron reflectometery emerged as a new field in the 1980s, after the discovery of giant magnetoresistance in antiferromagnetically-coupled multilayered films. Technique The technique involves shining a highly collimated beam of neutrons onto an extremely flat surface and measuring the intensity of reflected radiation as a function of angle or neutron wavelength. The exact shape of the reflectivity profile provides detailed information about the structure of the surface, including the thickness, density, and roughness of any thin films layered on th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neutron Research Facility
A neutron research facility is most commonly a big laboratory operating a large-scale neutron source that provides thermal neutrons to a suite of research instruments. The neutron source usually is a research reactor or a spallation source. In some cases, a smaller facility will provide high energy neutrons (e.g. 2.5 MeV or 14 MeV fusion neutrons) using existing neutron generator technologies. List of neutron facilities The following list is intended to be exhaustive and to cover active facilities as well as those that are shut down. ;Australia * ANSTO-HIFAR Reactor, Sydney * Open-pool Australian lightwater reactor (OPAL) ;Bangladesh * Atomic Energy Research Establishment (AERE), Bangladesh Atomic Energy Commission(BAEC) ;Canada * NRC Canadian Neutron Beam Centre at Chalk River Laboratories * RE-Labs Inc. – Single Event Effects Testing Services ;China * China Spallation Neutron Source – Dongguan, Guangdong. * CNPG – Light ion (D,T), China Institute of Atomic Ener ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
National Synchrotron Light Source
The National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL) in Upton, New York was a national user research facility funded by the U.S. Department of Energy (DOE). Built from 1978 through 1984, and officially shut down on September 30, 2014, the NSLS was considered a second-generation synchrotron. The NSLS experimental floor consisted of two electron storage rings: an X-ray ring and a VUV (vacuum ultraviolet) ring which provided intense, focused light spanning the electromagnetic spectrum from the infrared through X-rays. The properties of this light and the specially designed experimental stations, called beamlines, allowed scientists in many fields of research to perform experiments not otherwise possible at their own laboratories. History Ground was broken for the NSLS on September 28, 1978. The VUV ring began operations in late 1982 and the X-ray ring was commissioned in 1984. In 1986, a second phase of construction expanded the NSLS by , which adde ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DESY
The Deutsches Elektronen-Synchrotron (English ''German Electron Synchrotron''), commonly referred to by the abbreviation DESY, is a national research center in Germany. It operates particle accelerators used to investigate the structure of matter, and conducts a broad spectrum of inter-disciplinary scientific research in three main areas: particle and high energy physics; photon science, and the development, construction and operation of particle accelerators. Its name refers to its first project, an electron synchrotron. DESY is publicly financed by the Federal Republic of Germany, the States of Germany, and the German Research Foundation (DFG). DESY is a member of the Helmholtz Association and operates at sites in Hamburg and Zeuthen. Functions DESY's function is to conduct fundamental research. It specializes in particle accelerator development, construction and operation, particle physics research to explore the fundamental characteristics of matter and forces, includi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
European Synchrotron Radiation Facility
The European Synchrotron Radiation Facility (ESRF) is a joint research facility situated in Grenoble, France, supported by 22 countries (13 member countries: France, Germany, Italy, the UK, Spain, Switzerland, Belgium, the Netherlands, Denmark, Finland, Norway, Sweden, Russia; and 9 associate countries: Austria, Portugal, Israel, Poland, the Czech Republic, Hungary, Slovakia, India and South Africa). Some 8,000 scientists visit this particle accelerator each year, conducting upwards of 2,000 experiments and producing around 1,800 scientific publications. History Inaugurated in September 1994, it has an annual budget of around 100 million euros, employs over 630 people and is host to more than visiting scientists each year. In 2009, the ESRF began a first major improvement in its capacities. With the creation of the new ultra-stable experimental hall of 8,000 m2 in 2015, its X-rays are 100 times more powerful, with a power of 100 billion times that of hospital radiography d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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