| | - electron beam
- stream of electrons (as from a betatron) generated by heat (thermionic emission), bombardment of charged atoms or particles (secondary electron emission), or strong electric fields (field emission). Electrons may be ... [9 Related Articles]
- electron capture
- (from the article "electron capture") one of three processes of radioactive disintegration known as beta decay (q.v.).FIGUREcause of radioactive decayFigure 1: Radioactive decay of beryllium-7
- electron charge
- (symbol e), fundamental physical constant expressing the naturally occurring unit of electric charge, equal to 1.6021892 × 10−19 coulomb, or 4.80325 × 10−10 electrostatic unit (esu, or statcoulomb). In addition ... [2 Related Articles]
- electron correlation
- (from the article "crystal") ...solid. Any large imbalance of charge is prevented by the strong electrical attraction between the negative electrons and the positive ions, plus the strong repulsion between electrons. The phrase electron ...
- electron cyclotron resonance heating
- (from the article "fusion reactor") ...to the frequency at which a nucleus gyrates about a magnetic field line, this resonant nucleus absorbs energy from the wave. This technique is called ion cyclotron resonance heating. Similarly, ...
- electron cyclotron wave
- (from the article "plasma") ...splits into two components, referred to as the fast and slow Alfven waves, which propagate at different frequency-dependent speeds. At still higher frequencies these two waves (called the electron cyclotron ...
- electron diffraction
- interference effects owing to the wavelike nature of a beam of electrons when passing near matter. According to the proposal (1924) of the French physicist Louis de Broglie, electrons and ... [3 Related Articles]
- electron emission
- (from the article "electricity") A metal contains mobile electrons in a partially filled band of energy levels-i.e., the conduction band. These electrons, though mobile within the metal, are rather tightly bound to it. The ...
- electron energy loss spectroscopy
- (from the article "spectroscopy") An example of particle spectroscopy is a surface analysis technique known as electron energy loss spectroscopy (EELS) that measures the energy lost when low-energy electrons (typically 5-10 electron volts) collide ...
- electron flow
- (from the article "electron tube") ...possible is the electron's change in kinetic energy as it is accelerated or decelerated by an electric field. Because energy is conserved, the RF field will increase (amplification) if the ...
- electron gun
- electrode structure that produces and may control, focus, and deflect a beam of electrons, as in a television picture tube (see ), where the beam produces a visual pattern on ... [3 Related Articles]
- electron microscope
- (from the article "electron microscope") microscope that attains extremely high resolution using an electron beam instead of a beam of light to illuminate the object of study. See microscope.ILLUSTRATIONSscanning electron microscopeScanning electron microscope.Encyclopæ
- electron multiplier
- (from the article "mass spectrometry") The development of electronic techniques for television during the 1930s yielded a device of extraordinary sensitivity for measuring small electron beams-namely, the secondary electron multiplier. Although originally invented for the ...
- electron optics
- branch of physics that is concerned with beams of electrons, their deflection and focusing by electric and magnetic fields, their interference when crossing each other, and their diffraction or bending ...
- electron pair
- (from the article "electrophile") in chemistry, an atom or a molecule that in chemical reaction seeks an atom or molecule containing an electron pair available for bonding. Electrophilic substances are Lewis acids (compounds that ...
- electron paramagnetic resonance
- selective absorption of weak radio-frequency electromagnetic radiation (in the microwave region) by unpaired electrons in the atomic structure of certain materials that simultaneously are subjected to a constant, strong magnetic ... [3 Related Articles]
- electron paramagnetic resonance spectroscopy
- (from the article "analysis") In a manner that is similar to that described for nuclear magnetic resonance spectrometry, electron spin resonance spectrometry is used to study spinning electrons. The absorbed radiation falls in the ...
- electron promotion
- (from the article "chemical bonding") Valence bond theory runs into an apparent difficulty with CH4. The valence-shell electron configuration of carbon is 2s22px12py1, which suggests that it can form only two bonds to hydrogen atoms, ...
- electron scattering
- deflection of the path of electrons as they pass through a solid (typically a metal, semiconductor, or insulator). Deflections, or collisions, are caused by electrostatic forces operating between the negatively ... [1 Related Articles]
- electron shell
- (from the article "The electron structure of zinc group elements") In the quantum mechanical version of the Bohr atomic model, each of the allowed electron orbits is assigned a quantum number n that runs from 1 (for the orbit closest ...
- electron spectroscopy
- method of determining the energy with which electrons are bound in chemical species by measuring the kinetic energies of the electrons emitted upon bombardment of the species with X-ray or ... [1 Related Articles]
- electron spectroscopy for chemical analysis
- (from the article "surface analysis") Since the binding energies of the electrons emitted through XPS are discrete and atoms of different elements have different characteristic electron-binding energies, the emitted electron beam can provide a simple ...
- electron spin
- (from the article "chemical bonding") To produce the ground-state electron configuration of the next element, lithium (Z = 3), one more electron is added. However, that electron cannot occupy the 1s orbital, for it has ...
- electron storage ring
- (from the article "particle accelerator") Many storage rings have been constructed to study the interactions of electrons with positrons. The principal centres of this research are Cornell University; Stanford University; CERN; Tsukuba, Japan; Frascati, Italy; ...
- electron synchrotron
- (from the article "electron synchrotron") type of synchrotron designed to accelerate electrons to high energies (see synchrotron).major referenceparticle acceleratorElectron synchrotronsThe i
- electron transfer
- (from the article "Physical Sciences") The transfer of electrons from one atom to another is a key step in photochemical reactions, including those that underlie photosynthesis and commercial processes such as photography and xerography. Alexander ...
- electron transport
- (from the article "lipid") ...pass down the series of oxidation-reduction reactions and in the last reaction reduce molecular oxygen (O2) to water (H2O). This part of oxidative phosphorylation is called electron transport.
- electron trap
- (from the article "phosphorescence") ...so. The case for phosphorescence is illustrated in the Figure by B. There, interposed between the ground level and the excited level, is a level of intermediate energy, called a ...
- electron tube
- device usually consisting of a sealed glass or metal-ceramic enclosure that is used in electronic circuitry to control a flow of electrons. Among the common applications of vacuum tubes are ... [17 Related Articles]
- electron tunneling
- (from the article "electrochemical reaction") ...such states can be attained by the particle at a lower energy-content than that needed for its transfer over the top of the energy barrier, according to the classical view, ...
- electron volt
- unit of energy commonly used in atomic and nuclear physics, equal to the energy gained by an electron (a charged particle carrying unit electronic charge when the electrical potential at ... [6 Related Articles]
- electron-antineutrino
- (from the article "neutrino") ...through matter for a distance equal to the Earth's diameter, reacts with a proton or a neutron. Finally, in 1956 a team of American physicists led by Frederick Reines reported ...
- electron-beam lithography
- (from the article "nanotechnology") ...sources, such as extreme ultraviolet and X-ray, are being developed to allow lithographic printing techniques to reach dimensions from 10 to 100 nanometres. Scanning beam techniques such as electron-beam lithography ...
- electron-beam machining
- (from the article "machine tool") The EBM technique is used for cutting fine holes and slots in any material. In a vacuum chamber, a beam of high-velocity electrons is focused on a workpiece. The kinetic ...
- electron-beam welding
- (from the article "welding") In electron-beam welding, the workpiece is bombarded with a dense stream of high-velocity electrons. The energy of these electrons is converted to heat upon impact. A beam-focusing device is included, ...
- electron-capture detector
- (from the article "chromatography") ...to hydrocarbons, but it will not detect carrier gases, such as nitrogen, or highly oxidized materials, such as carbon dioxide, carbon monoxide, sulfur dioxide, and water. In another device, the ...
- electron-deficient compound
- (from the article "borane") ...different from any other class of compounds. Because the bonding in boranes involves multicentre bonding, in which three or more atoms share a pair of bonding electrons, boranes are commonly ...
- electron-exchange resin
- (from the article "ion-exchange resin") Two separate types of resins are commonly classed as ion-exchange resins, although their functions do not involve an interchange of ions. These are the chelating resins and the electron-exchange resins. ...
- electron-hole pair
- (from the article "materials science") ...band to the higher-energy conduction band. The electrons in the conduction band and the holes they have left behind in the valence band are both mobile and can be induced ...
- electron-neutrino
- (from the article "Physical Sciences") ...of the neutrino for which they were awarded the Nobel Prize for Physics in 2002. Neutrinos, the most elusive of stable fundamental particles, exist as three types: muon-neutrinos, tau-neutrinos, and ...
- electron-nuclear double resonance
- (from the article "magnetic resonance") ...other. Thus, an apparatus with two oscillating magnetic fields is employed, one for the driver and the other for the detector. Driving an NMR and detecting its effect on an ...
- electron-positron creation
- (from the article "antimatter") ...quanta of electromagnetic radiation. The inverse reaction gamma → e+ + e− can also proceed under appropriate conditions, and the process is called electron-positron creation, or pair production.
- electron-probe microanalyzer
- (from the article "microscope") Combinations of techniques have given rise to the scanning transmission electron microscope (STEM), which combines the methods of TEM and SEM, and the electron-probe microanalyzer, or microprobe analyzer, which allows ...
- electron-proton storage ring
- (from the article "particle accelerator") The Hadron-Electron Ring Accelerator (HERA) at the DESY laboratory stores both electrons and protons. It is the only machine that operates in this way with particles of different masses. To ...
- electronegativity
- in chemistry, the ability of an atom to attract to itself an electron pair shared with another atom in a chemical bond. [11 Related Articles]
- electroneutrality, law of
- (from the article "ceramic composition and properties") The second limitation on the types of crystal structure that can be adopted by ionically bonded atoms is based on a law of physics-that the crystal must remain electrically neutral. ...
- electronic activation
- (from the article "radiation") ...by interaction with radiation. In this energy-rich state it may undergo a variety of unusual chemical reactions that are normally not available to it in thermal equilibrium. Of special importance ...
- Electronic Arts, Inc.
- American developer and manufacturer of electronic games for personal computers (PCs) and video game consoles. Established in 1982 by William M. ("Trip") Hawkins, Electronic Arts (EA) now has a product ...
- electronic balance
- (from the article "balance") Balances of the late 20th century were usually electronic and far more accurate than mechanical balances. A scanner measured the displacement of the pan holding the object to be weighed ...
- electronic banking system
- (from the article "automation") ...alphanumeric characters at the bottom of checks. Bank balances are computed and recorded using computer systems installed by virtually all financial institutions. Major banks have established electronic banking systems, including ...
- electronic bulletin board
- (from the article "information processing") ...types of face-to-face encounters such as meetings, conferences, seminars, workshops, and classroom lectures-are being supplemented and in some cases replaced by e-mail, electronic bulletin boards (a technique of broadcasting newsworthy ...
- electronic carillon
- 20th-century musical instrument in which the acoustical tone source-metal tubes, rods, or bars struck by hammers-is picked up electromagnetically or electrostatically and converted into electrical vibrations that are highly amplified ...
- electronic communication network
- (from the article "stock exchange") Technological developments have greatly influenced the nature of trading. By the 21st century, increased access to the Internet and the proliferation of electronic communications networks (ECNs) had allowed electronic trading, ...
- electronic configuration
- the arrangement of electrons in energy levels around an atomic nucleus. According to the older shell atomic model, electrons occupy several levels from the first shell nearest the nucleus, K, ... [16 Related Articles]
- electronic countermeasure
- (from the article "military aircraft") ...part of the U.S. and Soviet nuclear forces after their deployment in 1975, 1985, and 1988, respectively. In common with all first-line combat aircraft, they were equipped with sophisticated electronic ...
- Electronic Data Systems
- (from the article "Perot, Ross") ...He was commissioned in the U.S. Navy in 1953 and served until 1957, after which he worked as a salesman for International Business Machines (IBM). In 1962 Perot quit IBM ...
- electronic detection system
- (from the article "airport") ...baggage both became subject to strict scrutiny following Sept. 11, 2001. Many additional airports installed X-ray equipment, for spotting metal items in baggage or concealed in clothing, and massive electronic ...
- electronic differentiator
- (from the article "differentiator") There are also electronic differentiators, or electrical differentiating circuits. The Figure shows a differentiator based on an electrical analog. For a time-varying input, if the capacitive reactance XC shown in ...
- Electronic Discrete Variable Automatic Computer
- (from the article "Computer patent wars") In 1945, with ENIAC nearing completion at the Moore School of Electrical Engineering of the University of Pennsylvania, planning began for ENIAC's successor, the Electronic Discrete Variable Automatic Computer (EDVAC). ...
- electronic eavesdropping
- the act of electronically intercepting conversations without the knowledge or consent of at least one of the participants. Historically, the most common form of electronic eavesdropping has been wiretapping, which ... [3 Related Articles]
- electronic encyclopaedia
- (from the article "encyclopaedia") Given the rapid pace of technological advancement in the contemporary world, it was to be expected that encyclopaedia publishers would seek ways to exploit new technologies in the field of ...
- electronic energy level
- (from the article "spectroscopy") Unlike the atom where the system is centrosymmetric (see above Foundations of atomic spectra: Basic atomic structure), the energy relationships among the nuclei and electrons in a diatomic molecule are ...
- electronic flash
- (from the article "photography, technology of") The most common flash system depends on a high-voltage discharge through a gas-filled tube. A capacitor charged to several hundred volts (by a step-up circuit from low-voltage batteries or from ...
- electronic funds transfer
- (from the article "money") Four very different types of transfer can be distinguished. First, depositors can use electronic funds transfers (EFTs) to withdraw currency from their accounts using automated teller machines (ATMs). In this ...
- electronic game
- any interactive game operated by computer circuitry. The machines, or "platforms," on which electronic games are played include general-purpose shared and personal computers, arcade consoles, video consoles connected to home ... [13 Related Articles]
- electronic instrument
- any musical instrument that produces or modifies sounds by electric, and usually electronic, means. The electronic element in such music is determined by the composer, and the sounds themselves are ... [6 Related Articles]
- electronic integrator
- (from the article "chromatography") ...adjusted for the detector response factor for that solute, is proportional to the amount of solute producing the peak. The area is frequently approximated from the peak width and height. ...
- electronic log
- (from the article "log") ...When the ship is moving, pressure in the forward-facing tube exceeds the pressure in the side tubes; this differential is transmitted to equipment that translates it into a speed measurement. ...
- electronic mail system
- (from the article "postal system") ...or chartered aircraft. New services based on communications and computer technology have been introduced. The Intelpost facsimile service operates nationally and with many other countries. An electronic mail system enables ...
- electronic monitor
- (from the article "prison") ...a corporate board; a corrupt politician may be blocked from holding future public office; and parents who abuse their children may be deprived of parental rights. Finally, new technologies, such ...
- electronic music
- any music involving electronic processing, e.g., recording and editing on tape, and whose reproduction involves the use of loudspeakers. [15 Related Articles]
- electronic organ
- keyboard musical instrument in which tone is generated by electronic circuits and radiated by loudspeaker. This instrument, which emerged in the early 20th century, was designed as an economical and ... [5 Related Articles]
- electronic paper
- (from the article "Xerox PARC") PARC continued to develop new ideas and technologies through the 1990s, but they were tethered to the Xerox mission of being The Document Company®. Among the most interesting innovations was ...
- electronic phototypesetter
- (from the article "printing") In phototypesetters of the third generation, the beam of light is replaced by a flow of electrons, which offers the advantage that the electrons can be deflected by means of ...
- electronic publishing
- (from the article "Internet") The Internet has become an invaluable and discipline-transforming environment for scientists and scholars. In 2004 Google began digitizing public-domain and out-of-print materials from several cooperating libraries in North America and ...
- electronic specific heat
- (from the article "superconductivity") ...the lattice vibrations (an amount that is the same for a system in the normal and in the superconducting state), and the remainder is used to increase the energy of ...
- electronic substrate and package ceramics
- advanced industrial materials that, owing to their insulating qualities, are useful in the production of electronic components.
- electronic switching
- (from the article "telephone and telephone system") As telephone traffic continued to grow through the years, it was realized that large numbers of common control circuits would be required to switch this traffic and that switches of ...
- electronic switching system
- (from the article "telephone and telephone system") Between 1960 and 1962 AT&T conducted a field trial of an electronic switching system (ESS) that employed a variety of new devices and concepts. Among these innovations was a gas-tube ...
- electronic system
- (from the article "electronics") branch of physics and electrical engineering that deals with the emission, behaviour, and effects of electrons and with electronic devices.automated assembly
- Electronic Trading
- The past few years have seen a spectacular and revolutionary development in the mechanics of stock trading-perhaps the largest change since brokers' fees were deregulated in 1975-electronic trading, or "e-trading." ... [4 Related Articles]
- electronic voltmeter
- (from the article "voltmeter") ...to measure voltage directly rather than by the effect of current. The potentiometer operates by comparing the voltage to be measured with known voltage; it is used to measure very ...
- electronic voting
- a form of computer-mediated voting in which voters make their selections with the aid of a computer. The voter usually chooses with the aid of a touch-screen display, although audio ...
- electronic watch
- (from the article "watch") ...pulses. Each oscillation of the balance operates a time-indicating gear train by advancing a toothed wheel one tooth. First produced in 1953, the resonance drive type, properly called an electronic ...
- electronic work function
- energy (or work) required to withdraw an electron completely from a metal surface. This energy is a measure of how tightly a particular metal holds its electrons-that is, of how ... [8 Related Articles]
- electronics
- branch of physics and electrical engineering that deals with the emission, behaviour, and effects of electrons and with electronic devices. [22 Related Articles]
- electronics intelligence
- (from the article "intelligence") Electronics intelligence (also called ELINT) is technical and intelligence information obtained from foreign electromagnetic emissions that are not radiated by communications equipment or by nuclear detonations and radioactive sources. By ...
- electronystagmography
- (from the article "ear, human") ...recorded by picking up the resulting rhythmical variations in the corneoretinal direct current potentials, using electrodes pasted to the skin of the temples-a diagnostic process called electronystagmography. An abnormal vestibular ...
- electroosmotic hypothesis
- (from the article "angiosperm") ...storage-lowers it. Thus a pressure gradient from the area of photosynthesis (source) to the region of growth or storage (sink) is established in sieve tubes that would allow solution flow. ...
- electrophile
- in chemistry, an atom or a molecule that in chemical reaction seeks an atom or molecule containing an electron pair available for bonding. Electrophilic substances are Lewis acids (compounds that ... [2 Related Articles]
- electrophilic aromatic substitution
- (from the article "organohalogen compound") Treatment of a compound that contains an aromatic ring with chlorine or bromine in the presence of a catalyst, typically iron (Fe) or an iron(III) halide (FeX3), brings about electrophilic ...
- electrophilic substitution
- (from the article "carboxylic acid") ...show not only the acidity and other reactions expected of carboxylic acids (as an acid, benzoic acid is slightly stronger than acetic acid) but, similar to other aromatic compounds, also ...
- electrophone
- any of a class of musical instruments in which the initial sound either is produced by electronic means or is conventionally produced (as by a vibrating string) and electronically amplified. ... [2 Related Articles]
- electrophoresis
- the movement of electrically charged particles in a fluid under the influence of an electric field. If the liquid rather than the particles is set in motion-e.g., through a fixed ... [12 Related Articles]
- electrophorus
- (from the article "Volta, Conte Alessandro") In 1775 Volta's interest in electricity led him to invent the electrophorus, a device used to generate static electricity. He became professor of physics at the Royal School of Como ...
- electrophotography
- any of several image-forming processes, principally xerography and the dielectric process, that rely on photoconductive substances whose electrical resistance decreases when light falls on them; it is the basis of ... [7 Related Articles]
- electrophysiology
- (from the article "mechanoreception") Slight deformation of any mechanoreceptive nerve cell ending results in electrical changes, called receptor or generator potentials, at the outer surface of the cell; this, in turn, induces the appearance ...
- electroplaque
- (from the article "bioelectricity") The basic element of a bioelectric organ is a flattened cell called an electroplaque. Large numbers of electroplaques are arranged in series and in parallel to build up voltage and ...
- electroplastic process
- (from the article "photography, technology of") In the electroplastic process a transparent thermoplastic serves as the photoconductive layer. After the plastic is charged and exposed, the residual electrostatic charge forms stresses in the thermoplastic. Controlled heating ...
- electroplating
- process of coating with metal by means of an electric current. Plating metal may be transferred to conductive surfaces (metals) or to nonconductive surfaces (plastics, wood, leather) after the latter ... [14 Related Articles]
- electropneumatic action
- (from the article "keyboard instrument") ...organ is then said to have a sliderless chest, and the most usual type is the pitman chest, so called because it contains a type of floating valve called a ...
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