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HREELS Spectrum
High resolution electron energy loss spectroscopy (HREELS) is a tool used in surface science. The inelastic scattering of electrons from surfaces is utilized to study electronic excitations or vibrational modes of the surface of a material or of molecules adsorbed to a surface. In contrast to other electron energy loss spectroscopies (EELS), HREELS deals with small energy losses in the range of 10−3 eV to 1 eV. It plays an important role in the investigation of surface structure, catalysis, dispersion of surface phonons and the monitoring of epitaxial growth. Overview of HREELS In general, electron energy loss spectroscopy is based on the energy losses of electrons when inelastically scattered on matter. An incident beam of electrons with a known energy (Ei) is scattered on a sample. The scattering of these electrons can excite the electronic structure of the sample. If this is the case the scattered electron loses the specific energy (ΔE) needed to cause the excitation. Those s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface Science
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid–gas interfaces. It includes the fields of ''surface chemistry'' and '' surface physics''. Some related practical applications are classed as surface engineering. The science encompasses concepts such as heterogeneous catalysis, semiconductor device fabrication, fuel cells, self-assembled monolayers, and adhesives. Surface science is closely related to interface and colloid science. Interfacial chemistry and physics are common subjects for both. The methods are different. In addition, interface and colloid science studies macroscopic phenomena that occur in heterogeneous systems due to peculiarities of interfaces. History The field of surface chemistry started with heterogeneous catalysis pioneered by Paul Sabatier on hydrogenation and Fritz Haber on the Haber process. Irving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amand Lucas
Amand Lucas (born 18 December 1936, Liège) is a Belgian scientist and professor at the Facultés Universitaires Notre-Dame de la Paix, at the Institute for Studies in Interface Sciences.Ritchie R.H., Lambin P., Lambert D., Vigneron J.P. Echenique P., In honor of Professor Amand A. Lucas on the occasion of his retirement, Journal of Electron Spectroscopy and Related Phenomena, Volume 129, Number 2, June 2003, pp. 83–85. In 1985, he was awarded the Francqui Prize The Francqui Prize is a prestigious Belgian scholarly and scientific prize named after Émile Francqui. Normally annually since 1933, the Francqui Foundation awards it in recognition of the achievements of a scholar or scientist, who at the start ... on Exact Sciences for his work on theoretical physics. References Belgian physicists Walloon people Living people Université de Namur faculty 1936 births {{Belgium-scientist-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scientific Techniques
A scientific technique is any systematic way of obtaining information about a scientific nature or to obtain a desired material or product. Scientific techniques can be divided in many different groups, e.g.: # Preparative techniques ## Synthesis techniques, e.g. the use of Grignard reagents in organic chemistry ## Growth techniques, e.g. crystal growth or cell cultures in biology ## Purification techniques e.g. those in chemistry # Measurement techniques ## Analysis techniques, e.g. ones that reveal atomic or molecular composition. ## Characterization techniques, e.g. ones that measure a certain property of a material. ## Imaging techniques, e.g. microscopy In some cases these methods have evolved into instrumental techniques that require expensive equipment. This is particularly true in sciences like physics, chemistry, and astronomy. It is customary to abbreviate the names of techniques into acronyms, although this does not hold for all of them. Particularly the advent of th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Energy Loss Spectroscopy
In electron energy loss spectroscopy (EELS) a material is exposed to a beam of electrons with a known, narrow range of kinetic energies. Some of the electrons will undergo inelastic scattering, which means that they lose energy and have their paths slightly and randomly deflected. The amount of energy loss can be measured via an electron spectrometer and interpreted in terms of what caused the energy loss. Inelastic interactions include phonon excitations, inter- and intra-band transitions, plasmon excitations, inner shell ionizations, and Cherenkov radiation. The inner-shell ionizations are particularly useful for detecting the elemental components of a material. For example, one might find that a larger-than-expected number of electrons comes through the material with 285 eV less energy than they had when they entered the material. This is approximately the amount of energy needed to remove an inner-shell electron from a carbon atom, which can be taken as evidence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mu-metal
Mu-metal is a nickel–iron soft ferromagnetic alloy with very high permeability, which is used for shielding sensitive electronic equipment against static or low-frequency magnetic fields. It has several compositions. One such composition is approximately 77% nickel, 16% iron, 5% copper, and 2% chromium or molybdenum. More recently, mu-metal is considered to be ASTM A753 Alloy 4 and is composed of approximately 80% nickel, 5% molybdenum, small amounts of various other elements such as silicon, and the remaining 12 to 15% iron. The name came from the Greek letter mu ( μ) which represents permeability in physics and engineering formulas. A number of different proprietary formulations of the alloy are sold under trade names such as ''MuMETAL'', ''Mumetall'', and ''Mumetal2''. Mu-metal typically has relative permeability values of 80,000–100,000 compared to several thousand for ordinary steel. It is a "soft" ferromagnetic material; it has low magnetic anisotropy and magnetos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Electron Multiplier
Channel, channels, channeling, etc., may refer to: Geography * Channel (geography), in physical geography, a landform consisting of the outline (banks) of the path of a narrow body of water. Australia * Channel Country, region of outback Australia in Queensland and partly in South Australia, Northern Territory and New South Wales. * Channel Highway, a regional highway in Tasmania, Australia. Europe * Channel Islands, an archipelago in the English Channel, off the French coast of Normandy * Channel Tunnel or Chunnel, a rail tunnel underneath the English Channel * English Channel, called simply "The Channel", the part of the Atlantic Ocean that separates Great Britain from northern France North America * Channel Islands of California, a chain of eight islands located in the Pacific Ocean off the coast of Southern California, United States * Channel Lake, Illinois, a census-designated place in Lake County, Illinois, United States * Channels State Forest, a state forest in Virginia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Concentric Hemispherical Analyser
In geometry, two or more objects are said to be concentric, coaxal, or coaxial when they share the same center or axis. Circles, regular polygons and regular polyhedra, and spheres may be concentric to one another (sharing the same center point), as may cylinders (sharing the same central axis). Geometric properties In the Euclidean plane, two circles that are concentric necessarily have different radii from each other.. However, circles in three-dimensional space may be concentric, and have the same radius as each other, but nevertheless be different circles. For example, two different meridians of a terrestrial globe are concentric with each other and with the globe of the earth (approximated as a sphere). More generally, every two great circles on a sphere are concentric with each other and with the sphere. By Euler's theorem in geometry on the distance between the circumcenter and incenter of a triangle, two concentric circles (with that distance being zero) are the circu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HREELS Spectrometer
High resolution electron energy loss spectroscopy (HREELS) is a tool used in surface science. The inelastic scattering of electrons from surfaces is utilized to study electronic excitations or vibrational modes of the surface of a material or of molecules adsorbed to a surface. In contrast to other electron energy loss spectroscopies (EELS), HREELS deals with small energy losses in the range of 10−3 eV to 1 eV. It plays an important role in the investigation of surface structure, catalysis, dispersion of surface phonons and the monitoring of epitaxial growth. Overview of HREELS In general, electron energy loss spectroscopy is based on the energy losses of electrons when inelastically scattered on matter. An incident beam of electrons with a known energy (Ei) is scattered on a sample. The scattering of these electrons can excite the electronic structure of the sample. If this is the case the scattered electron loses the specific energy (ΔE) needed to cause the excitation. Those s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
T-symmetry
T-symmetry or time reversal symmetry is the theoretical symmetry of physical laws under the transformation of time reversal, : T: t \mapsto -t. Since the second law of thermodynamics states that entropy increases as time flows toward the future, in general, the macroscopic universe does not show symmetry under time reversal. In other words, time is said to be non-symmetric, or asymmetric, except for special equilibrium states when the second law of thermodynamics predicts the time symmetry to hold. However, quantum noninvasive measurements are predicted to violate time symmetry even in equilibrium, contrary to their classical counterparts, although this has not yet been experimentally confirmed. Time ''asymmetries'' generally are caused by one of three categories: # intrinsic to the dynamic physical law (e.g., for the weak force) # due to the initial conditions of the universe (e.g., for the second law of thermodynamics) # due to measurements (e.g., for the noninvasive measur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Mechanical Dispersion Theory
In physics, a quantum (plural quanta) is the minimum amount of any physical entity (physical property) involved in an interaction. The fundamental notion that a physical property can be "quantized" is referred to as "the hypothesis of quantization". This means that the magnitude of the physical property can take on only discrete values consisting of integer multiples of one quantum. For example, a photon is a single quantum of light (or of any other form of electromagnetic radiation). Similarly, the energy of an electron bound within an atom is quantized and can exist only in certain discrete values. (Atoms and matter in general are stable because electrons can exist only at discrete energy levels within an atom.) Quantization is one of the foundations of the much broader physics of quantum mechanics. Quantization of energy and its influence on how energy and matter interact (quantum electrodynamics) is part of the fundamental framework for understanding and describing nature. E ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microscopic Theory
A microscopic theory is one that contains an explanation at the atomic or subatomic level in contrast to a higher level or classical macroscopic or ''phenomenological theory''. e.g. in superconductivity BCS theory BCS theory or Bardeen–Cooper–Schrieffer theory (named after John Bardeen, Leon Cooper, and John Robert Schrieffer) is the first microscopic theory of superconductivity since Heike Kamerlingh Onnes's 1911 discovery. The theory describes sup ... is a microscopic theory. References {{atomic-physics-stub Atomic, molecular, and optical physics ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Perfect Conductor
A perfect conductor or perfect electric conductor (PEC) is an idealized material exhibiting infinite electrical conductivity or, equivalently, zero resistivity (cf. perfect dielectric). While perfect electrical conductors do not exist in nature, the concept is a useful model when electrical resistance is negligible compared to other effects. One example is ideal magnetohydrodynamics, the study of perfectly conductive fluids. Another example is electrical circuit diagrams, which carry the implicit assumption that the wires connecting the components have no resistance. Yet another example is in computational electromagnetics, where PEC can be simulated faster, since the parts of equations that take finite conductivity into account can be neglected. Properties of perfect conductors Perfect conductors: *have exactly zero electrical resistance - a steady current within a perfect conductor will flow without losing energy to resistance. Resistance is what causes heating in conductors, t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
