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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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macroscopic
The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments. It is the opposite of microscopic. Overview When applied to physical phenomena and bodies, the macroscopic scale describes things as a person can directly perceive them, without the aid of magnifying devices. This is in contrast to observations ( microscopy) or theories ( microphysics, statistical physics) of objects of geometric lengths smaller than perhaps some hundreds of micrometres. A macroscopic view of a ball is just that: a ball. A microscopic view could reveal a thick round skin seemingly composed entirely of puckered cracks and fissures (as viewed through a microscope) or, further down in scale, a collection of molecules in a roughly spherical shape (as viewed through an electron microscope). An example of a physical theory that takes a deliberately macroscopic viewpoint is thermodynamics. An exampl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low-energy Electron Diffraction
Low-energy electron diffraction (LEED) is a technique for the determination of the surface structure of single crystal, single-crystalline materials by bombardment with a collimated beam of low-energy electrons (30–200 eV) and observation of diffracted electrons as spots on a fluorescent screen. LEED may be used in one of two ways: # Qualitatively, where the diffraction pattern is recorded and analysis of the spot positions gives information on the symmetry of the surface structure. In the presence of an adsorbate the qualitative analysis may reveal information about the size and rotational alignment of the adsorbate unit cell with respect to the substrate unit cell. # Quantitatively, where the intensities of diffracted beams are recorded as a function of incident electron beam energy to generate the so-called I–V curves. By comparison with theoretical curves, these may provide accurate information on atomic positions on the surface at hand. Historical perspective An el ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palladium
Palladium is a chemical element; it has symbol Pd and atomic number 46. It is a rare and lustrous silvery-white metal discovered in 1802 by the English chemist William Hyde Wollaston. He named it after the asteroid Pallas (formally 2 Pallas), which was itself named after the epithet of the Greek goddess Athena, acquired by her when she slew Pallas. Palladium, platinum, rhodium, ruthenium, iridium and osmium form together a group of elements referred to as the platinum group metals (PGMs). They have similar chemical properties, but palladium has the lowest melting point and is the least dense of them. More than half the supply of palladium and its congener platinum is used in catalytic converters, which convert as much as 90% of the harmful gases in automobile exhaust (hydrocarbons, carbon monoxide, and nitrogen dioxide) into nontoxic substances (nitrogen, carbon dioxide and water vapor). Palladium is also used in electronics, dentistry, medicine, hydrogen purification ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen
Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter. Under standard conditions, hydrogen is a gas of diatomic molecules with the chemical formula, formula , called dihydrogen, or sometimes hydrogen gas, molecular hydrogen, or simply hydrogen. Dihydrogen is colorless, odorless, non-toxic, and highly combustible. Stars, including the Sun, mainly consist of hydrogen in a plasma state, while on Earth, hydrogen is found as the gas (dihydrogen) and in molecular forms, such as in water and organic compounds. The most common isotope of hydrogen (H) consists of one proton, one electron, and no neutrons. Hydrogen gas was first produced artificially in the 17th century by the reaction of acids with metals. Henry Cavendish, in 1766–1781, identified hydrogen gas as a distinct substance and discovere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gerhard Ertl
Gerhard Ertl (; born 10 October 1936) is a German physicist and a Professor emeritus at the Department of Physical Chemistry, Fritz-Haber-Institut der Max-Planck-Gesellschaft in Berlin, Germany. Ertl's research laid the foundation of modern surface chemistry, which has helped explain how fuel cells produce energy without pollution, how catalytic converters clean up car exhausts and even why iron rusts, the Royal Swedish Academy of Sciences said. His work has paved the way for development of cleaner energy sources and will guide the development of fuel cells, said Astrid Graslund, secretary of the Nobel Committee for Chemistry. He was awarded the 2007 Nobel Prize in Chemistry for his studies of chemical processes on solid surfaces. The Nobel academy said Ertl provided a detailed description of how chemical reactions take place on surfaces. His findings applied in both academic studies and industrial development, the academy said. “Surface chemistry can even explain the destru ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langmuir Equation
Langmuir may refer to: * Langmuir (crater), an impact crater on the Moon's far side * Langmuir (journal), ''Langmuir'' (journal), an academic journal on colloids, surfaces and interfaces, published by the American Chemical Society * Langmuir (unit), a unit of exposure of an adsorbate/gas to a substrate used in surface science to study adsorption * Arrowsmith Peninsula#Named features, Langmuir Cove, a cove in the north end of Arrowsmith Peninsula, Graham Land, Antarctica * Langmuir monolayer, a one-molecule thick layer of an insoluble organic material spread onto an aqueous subphase in a Langmuir-Blodgett trough People * Alexander Langmuir (1910–1993), American epidemiologist * Gavin I. Langmuir (1924–2005), Canadian veteran of World War II, historian of anti-Semitism and medievalist at Stanford University * Irving Langmuir (1881–1957), American Nobel Prize-winning chemist and physicist See also * {{disambiguation, surname ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Langmuir (journal)
''Langmuir'' is a peer-reviewed scientific journal that was established in 1985 and is published by the American Chemical Society. It is the leading journal focusing on the science and application of systems and materials in which the interface dominates structure and function. Research areas covered include surface and colloid chemistry. Langmuir publishes original research articles, invited feature articles, perspectives, and editorials. The title honors Irving Langmuir, winner of the 1932 Nobel Prize for Chemistry. The founding editor-in-chief was Arthur W. Adamson. Abstracting and indexing ''Langmuir'' is indexed in Chemical Abstracts Service, Scopus, EBSCOhost, British Library, PubMed, Web of Science The Web of Science (WoS; previously known as Web of Knowledge) is a paid-access platform that provides (typically via the internet) access to multiple databases that provide reference and citation data from academic journals, conference proceedi ..., and SwetsWise. Refe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Irving Langmuir
Irving Langmuir (; January 31, 1881 – August 16, 1957) was an American chemist, physicist, and metallurgical engineer. He was awarded the Nobel Prize in Chemistry in 1932 for his work in surface chemistry. Langmuir's most famous publication is the 1919 article "The Arrangement of Electrons in Atoms and Molecules" in which, building on Gilbert N. Lewis's cubical atom theory and Walther Kossel's chemical bonding theory, he outlined his "concentric theory of atomic structure". Langmuir became embroiled in a priority dispute with Lewis over this work; Langmuir's presentation skills were largely responsible for the popularization of the theory, although the credit for the theory itself belongs mostly to Lewis. While at General Electric from 1909 to 1950, Langmuir advanced several fields of physics and chemistry, inventing the gas-filled incandescent lamp and the hydrogen welding technique. The Langmuir Laboratory for Atmospheric Research near Socorro, New Mexico, was named ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haber Process
The Haber process, also called the Haber–Bosch process, is the main industrial procedure for the ammonia production, production of ammonia. It converts atmospheric nitrogen (N2) to ammonia (NH3) by a reaction with hydrogen (H2) using finely divided iron metal as a catalyst: \ce \qquad This reaction is exothermic but disfavored in terms of entropy because four equivalents of reactant gases are converted into two equivalents of product gas. As a result, high pressures and temperatures that are not too high are needed to Le_Chatelier's_principle, drive the reaction forward. The German chemists Fritz Haber and Carl Bosch developed the process in the first decade of the 20th century, and its improved efficiency over existing methods such as the Birkeland–Eyde process, Birkeland-Eyde and Frank–Caro process, Frank-Caro processes was a major advancement in the industrial production of ammonia. The Haber process can be combined with steam reforming to produce ammonia with just ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fritz Haber
Fritz Jakob Haber (; 9 December 1868 – 29 January 1934) was a German chemist who received the Nobel Prize in Chemistry in 1918 for his invention of the Haber process, a method used in industry to synthesize ammonia from nitrogen gas and hydrogen gas. This invention is important for the large-scale synthesis of fertilizers and Explosive material, explosives. It is estimated that a third of annual global food production uses ammonia from the Haber–Bosch process, and that this food supports nearly half the world's population. For this work, Haber has been called one of the most important scientists and industrial chemists in human history. Haber also, along with Max Born, proposed the Born–Haber cycle as a method for evaluating the lattice energy of an ionic solid. Haber, a known German nationalist, is also considered the "father of chemical warfare" for his years of pioneering work developing and Chlorine#Use as a weapon, weaponizing chlorine and other poisonous gases during ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogenation
Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to redox, reduce or Saturated and unsaturated compounds, saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces Double bond, double and Triple bond, triple bonds in hydrocarbons. Process Hydrogenation has three components, the Saturated and unsaturated compounds, unsaturated substrate, the hydrogen (or hydrogen source) and, invariably, a catalyst. The redox, reduction reaction is carried out at different temperatures and pressures depending upon the substrate and the activity of the catalyst. Related or competing reactions The same cataly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
