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Ethynyl Radical
The ethynyl radical (systematically named λ3-ethyne and hydridodicarbon(''C''—''C'')) is an organic compound with the chemical formula C≡CH (also written CHor ). It is a simple molecule that does not occur naturally on Earth but is abundant in the interstellar medium. It was first observed by electron spin resonance isolated in a solid argon matrix at liquid helium temperatures in 1963 by Cochran and coworkers at the Johns Hopkins Applied Physics Laboratory. It was first observed in the gas phase by Tucker and coworkers in November 1973 toward the Orion Nebula, using the NRAO 11-meter radio telescope. It has since been detected in a large variety of interstellar environments, including dense molecular clouds, bok globules, star forming regions, the shells around carbon-rich evolved stars, and even in other galaxies. Astronomical Importance Observations of C2H can yield a large number of insights into the chemical and physical conditions where it is located. First, the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Organic Compound
In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. The study of the properties, reactions, and syntheses of organic compounds comprise the discipline known as organic chemistry. For historical reasons, a few classes of carbon-containing compounds (e.g., carbonate salts and cyanide salts), along with a few other exceptions (e.g., carbon dioxide, hydrogen cyanide), are not classified as organic compounds and are considered inorganic. Other than those just named, little consensus exists among chemists on precisely which carbon-containing compounds are excluded, making any rigorous definition of an organic compound elusive. Although organic compounds make up only a small percentage of Earth's crust, they are of central importance because all known life is based on organic compounds. Living t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fractionation
Fractionation is a separation process in which a certain quantity of a mixture (of gases, solids, liquids, enzymes, or isotopes, or a suspension) is divided during a phase transition, into a number of smaller quantities (fractions) in which the composition varies according to a gradient. Fractions are collected based on differences in a specific property of the individual components. A common trait in fractionations is the need to find an optimum between the amount of fractions collected and the desired purity in each fraction. Fractionation makes it possible to isolate more than two components in a mixture in a single run. This property sets it apart from other separation techniques. Fractionation is widely employed in many branches of science and technology. Mixtures of liquids and gases are separated by fractional distillation by difference in boiling point. Fractionation of components also takes place in column chromatography by a difference in affinity between stationary p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbon Monoxide
Carbon monoxide (chemical formula CO) is a colorless, poisonous, odorless, tasteless, flammable gas that is slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the simplest molecule of the oxocarbon family. In coordination complexes the carbon monoxide ligand is called carbonyl. It is a key ingredient in many processes in industrial chemistry. The most common source of carbon monoxide is the partial combustion of carbon-containing compounds, when insufficient oxygen or heat is present to produce carbon dioxide. There are also numerous environmental and biological sources that generate and emit a significant amount of carbon monoxide. It is important in the production of many compounds, including drugs, fragrances, and fuels. Upon emission into the atmosphere, carbon monoxide affects several processes that contribute to climate change. Carbon monoxide has important biological roles across phylogenetic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Propynylidyne
Propynylidyne is a chemical compound that has been identified in interstellar space. Structure Linear (''l''-C3H) μD=3.551 Debye 2Π electronic ground state Simulated spectrum A rotational spectrum of the 2Π electronic ground state of ''l''-C3H can be made using the PGopher software (a Program for Simulating Rotational Structure, C. M. Western, University of Bristol, http://pgopher.chm.bris.ac.uk) and molecular constants extracted from the literature. These constants include μ=3.551 Debye and others provided by Yamamoto et al. 1990, given in units of MHz: B=11189.052, D=0.0051365, ASO=432834.31, γ=-48.57, p=-7.0842, and q=-13.057. A selection rule of ΔJ=0,1 was applied, with S=0.5. The resulting simulation for the rotational spectrum of C3H at a temperature of 30 K agree well with observations. The simulated spectrum is shown in the figure at right with the approximate atmospheric transmission overplotted in blue. All of the strongest simulated lines wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vinyl Radical
Vinyl may refer to: Chemistry * Polyvinyl chloride (PVC), a particular vinyl polymer * Vinyl cation, a type of carbocation * Vinyl group, a broad class of organic molecules in chemistry * Vinyl polymer, a group of polymers derived from vinyl monomers Materials * PVC clothing, a fabric * Vinyl composition tile, a type of floor tiling * Vinyl siding, an exterior building cladding Music * LP Records, commonly referred to as "vinyl" because they are made with PVC, a co-polymer of vinyl chloride acetate. * ''Vinyl'' (Dramarama album), 1991 * ''Vinyl'' (William Michael Morgan album), 2016 * ''Vinyl'' (EP), by Dramarama * Vinyl Solution, a record label * "Vinyl", a song by Kira Kosarin Film * ''Vinyl'' (1965 film), directed by Andy Warhol * ''Vinyl'' (2000 film), a documentary directed by Alan Zweig * ''Vinyl'' (2012 film), directed by Sara Sugarman about a 2004 musical hoax involving UK band, The Alarm Television * ''Vinyl'' (TV series), a 2016 American television series o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumstellar Envelope
A circumstellar envelope (CSE) is a part of a star that has a roughly spherical shape and is not gravitationally bound to the star core. Usually circumstellar envelopes are formed from the dense stellar wind, or they are present before the formation of the star. Circumstellar envelopes of old stars (Mira variables and OH/IR stars) eventually evolve into protoplanetary nebulae, and circumstellar envelopes of young stellar objects evolve into circumstellar discs. Types of circumstellar envelopes * Circumstellar envelopes of AGB stars * Circumstellar envelopes around young stellar objects See also * Circumstellar dust * Common envelopes * Stellar evolution Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is cons ... References External links The Structure and Evolution of Envelopes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stellar Wind
A stellar wind is a flow of gas ejected from the upper atmosphere of a star. It is distinguished from the bipolar outflows characteristic of young stars by being less collimated, although stellar winds are not generally spherically symmetric. Different types of stars have different types of stellar winds. Post-main-sequence stars nearing the ends of their lives often eject large quantities of mass in massive ( \scriptstyle \dot > 10^ solar masses per year), slow (v = 10 km/s) winds. These include red giants and supergiants, and asymptotic giant branch stars. These winds are understood to be driven by radiation pressure on dust condensing in the upper atmosphere of the stars. Young T Tauri stars often have very powerful stellar winds. Massive stars of types O and B have stellar winds with lower mass loss rates (\scriptstyle \dot 1–2000 km/s). Such winds are driven by radiation pressure on the resonance absorption lines of heavy elements such as carbon and nitr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glow Discharge
A glow discharge is a plasma formed by the passage of electric current through a gas. It is often created by applying a voltage between two electrodes in a glass tube containing a low-pressure gas. When the voltage exceeds a value called the striking voltage, the gas ionization becomes self-sustaining, and the tube glows with a colored light. The color depends on the gas used. Glow discharges are used as a source of light in devices such as neon lights, fluorescent lamps, and plasma-screen televisions. Analyzing the light produced with spectroscopy can reveal information about the atomic interactions in the gas, so glow discharges are used in plasma physics and analytical chemistry. They are also used in the surface treatment technique called sputtering. Electrical conduction in gas Conduction in a gas requires charge carriers, which can be either electrons or ions. Charge carriers come from ionizing some of the gas molecules. In terms of current flow, glow discharge falls ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Photolysis
Photodissociation, photolysis, photodecomposition, or photofragmentation is a chemical reaction in which molecules of a chemical compound are broken down by photons. It is defined as the interaction of one or more photons with one target molecule. Photodissociation is not limited to visible light. Any photon with sufficient energy can affect the chemical bonds of a chemical compound. Since a photon energy, photon's energy is inversely proportional to its wavelength, electromagnetic radiations with the energy of visible light or higher, such as ultraviolet light, x-rays, and gamma rays can induce such reactions. Photolysis in photosynthesis Photolysis is part of the light-dependent reactions, light-dependent reaction or light phase or photochemical phase or Hill reaction of photosynthesis. The general reaction of photosynthetic photolysis can be given in terms of photons as: :\ce + 2 \text \longrightarrow \ce The chemical nature of "A" depends on the type of organism. Purple su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyanide
Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of a carbon atom triple-bonded to a nitrogen atom. In inorganic cyanides, the cyanide group is present as the anion . Soluble salts such as sodium cyanide (NaCN) and potassium cyanide (KCN) are highly toxic. Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liquid that is produced on a large scale industrially. It is obtained by acidification of cyanide salts. Organic cyanides are usually called nitriles. In nitriles, the group is linked by a covalent bond to carbon. For example, in acetonitrile (), the cyanide group is bonded to methyl (). Although nitriles generally do not release cyanide ions, the cyanohydrins do and are thus rather toxic. Bonding The cyanide ion is isoelectronic with carbon monoxide a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Zeeman Effect
The Zeeman effect (; ) is the effect of splitting of a spectral line into several components in the presence of a static magnetic field. It is named after the Dutch physicist Pieter Zeeman, who discovered it in 1896 and received a Nobel prize for this discovery. It is analogous to the Stark effect, the splitting of a spectral line into several components in the presence of an electric field. Also similar to the Stark effect, transitions between different components have, in general, different intensities, with some being entirely forbidden (in the dipole approximation), as governed by the selection rules. Since the distance between the Zeeman sub-levels is a function of magnetic field strength, this effect can be used to measure magnetic field strength, e.g. that of the Sun and other stars or in laboratory plasmas. The Zeeman effect is very important in applications such as nuclear magnetic resonance spectroscopy, electron spin resonance spectroscopy, magnetic resonance imagin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
