atoms in a plane. Each carbon atom contributes one electron to a delocalized system of electrons that is also a part of the chemical bonding. The delocalized electrons are free to move throughout the plane ...Image Benz4.png thumb right 200px Benzene , with the delocalization of the electron s indicated by the circle. In chemistry, delocalized electrons are electron s in a molecule , ion or solid metal that are not associated with a single atom or one covalent bond . ref IUPAC Gold Book http goldbook.iupac.org D01583.html delocalization ref Delocalized electrons are contained within an Molecular orbital orbital that extends over several adjacent atoms. Classically, delocalized electrons can be found in conjugated system s and mesoionic compounds. It is increasingly appreciated that electrons in Sigma bonds sigma bonding levels are also delocalized. For example, in methane , the bonding electrons are shared by all five atoms equally. Pervasive existence of delocalization is implicit in molecular orbital theory . Examples In the simple aromatic ring of benzene the delocalization of six Pi bond electrons over the C sub 6 sub ring is often graphically indicated by a circle. The fact that the six C C bonds are equidistant is one indication of this delocalization. In valence bond theory , delocalization in benzene is represented by resonance chemistry resonance structures . Delocalized electrons ... of delocalized electrons. This means that the electrons are free to move throughout the structure ... delocalized charge charge delocalization when meaning delocalized electrons. An example of delocalized electrons delocalized charge in ions can be found in the carboxylate group, wherein the negative ... delocalized is the charge in an anion the stronger is its conjugate acid . For example, the negative ...&ndash 11793 doi 10.1021 jp105670t ref Delocalization in reactions Delocalized electrons are important ... References reflist Category Chemical bonding Category Electron states ar ca Deslocalitzaci ... more details
into single line entries. Infobox Particle name Electron image File Crookes tube in use lateral view standing cross prPNr 11.jpg 280px alt A glass tube containing a glowing green electron beam caption ... Rays A History of J J Thomson s Electron url http books.google.com ?id xUzaWGocMdMC&printsec ... Warwick first2 A. year 2001 title Histories of the Electron The Birth of Microphysics url http ... 44 page 293 ref symbol SubatomicParticle Electron , SubatomicParticle beta mass val 9.10938291 ... electric charge val 1 el e ref group note The electron s charge is the negative of elementary ... Bohr magneton sub B sub ref name 2010 CODATA spin frac 1 2 The electron symbol SubatomicParticle Electron is a subatomic particle with a negative elementary charge elementary electric charge . It has ... . ref name prl50 An electron has a rest mass mass that is approximately Proton to electron mass ... spin of the electron is a half integer value in units of reduced Planck constant , which means that it is a fermion . The antiparticle of the electron is called the positron it is identical to the electron .... When an electron positron annihilation electron collides with a positron , both particles may be totally ... mass. Since an electron is a fermion, no two electrons can occupy the same quantum state ... electron was introduced for this charge in 1894 by Irish physicist George Johnstone Stoney . The electron .... An electron in motion relative to an observer generates a magnetic field , and will be deflected by external magnetic fields. When an electron is accelerated, it can absorb or radiate energy in the form ... Coulomb s law Coulomb force between an electron and a proton causes electrons to be Binding energy ... individual electrons as well as Plasma physics electron plasma , whereas dedicated telescope s can detect electron plasma in outer space. Electrons have many applications, including Electron beam welding welding , cathode ray tube s, electron microscope s, radiation therapy , free electron laser lasers ... more details
Wiktionarypar electron An electron is a subatomic particle. Electron may also refer to Electron bird , a genus of birds Electron vehicle , an electric urban vehicle concept by AMC Electron computer hacker , a member of an Australian hacking group Acorn Electron , an 8 bit computer by Acorn Computers Ltd Visa Electron , a brand of credit or debit cards Electron engine , a video game engine by Obsidian Entertainment L 188W Electron , an Argentine Navy version of the Lockheed L 188 Electra Electron comic book character , character by Apokalupsis Webcomics Electron or elementary charge e See also Elektron alloy , a range of magnesium alloys Electro disambiguation Elektron disambiguation Electrum disambig ast Electr n dixebra fr Electron la Electron discretiva nl Electron pl Electron uk ... more details
Unreferenced stub auto yes date December 2009 Electron excitation is the movement of an electron to a higher energy state . This can either be done by photoexcitation PE , where the original electron absorbs the photon and gains all the photon s energy or by electrical Excited state excitation EE , where the original electron absorbs the energy of another, energetic electron. Within a semiconductor crystal lattice, thermal excitation is a process where lattice vibrations provide enough energy to move electrons to a higher energy band . When an excited electron falls back to a lower energy state again, it is called electron relaxation . This can be done by radiation of a photon or giving the energy to a third spectator particle as well. DEFAULTSORT Electron Excitation Category Electron Physics stub ja ... more details
Unreferenced stub auto yes date December 2009 Electron deficiency occurs when a compound has too few valence electron s for the connections between atoms to be described as covalent bond s. Electron deficient bonds are often better described as 3 center 2 electron bond s. Examples of compounds that are electron deficient are the borane s. The term electron deficient is also used in a more general way in organic chemistry , to indicate a pi bonding pi system such as an alkene or arene that has Polar effect electron withdrawing groups attached, as found in nitrobenzene or acrylonitrile . Instead of showing the nucleated character common with simple C C bonds, electron deficient pi systems may be electrophile electrophilic and susceptible to nucleophilic attack, as is seen in the Michael addition or in nucleophilic aromatic substitution . As the most extreme form of highly localize electron deficiency one can consider the metallic bond . DEFAULTSORT Electron Deficiency Category Chemical bonding Chem stub ar de Elektronenmangelbindung nl Elektronendefici ntie pt Defici ncia de el trons zh ... more details
Electron scattering is the process whereby an electron is deflected from its original trajectory . As they are charged particle s, they are subject to electromagnetic force s. Phenomena Electrons can be scattering scattered by other charged particles through the Coulomb s law electrostatic Coulomb forces . Furthermore, if a magnetic field is present, a traveling electron will be deflected by the Lorentz force . An extremely accurate description of all electron scattering, including quantum and relativistic aspects, is given by the theory of quantum electrodynamics . Types Common electron scattering processes include Compton scattering , in which an electron absorbs a photon and reemits it, changing the energy and momentum of both M ller scattering , in which two electrons scatter off of one another Bhabha scattering , in which an electron and a positron scatter Bremsstrahlung , in which an electron most commonly, but also any other particle passes by a heavy charged object like a nucleus , changes energy and direction, and emits a photon Deep inelastic scattering , in which a high energy electron interacts with a nucleus and breaks it up Synchrotron emission , in which an electron interacts with an external magnetic field, changes direction, and emits a photon. physics stub DEFAULTSORT Electron Scattering Category Electron Category Scattering de Elektronenstreuung it Scattering di elettroni ... more details
An electron orbital may refer to An atomic orbital , describing the behaviour of an electron in an atom A molecular orbital , describing the behaviour of an electron in a molecule See also Electron configuration , the arrangement of electrons in structures such as atoms or molecules Orbital hybridization , a combining of atomic orbitals to form an equal number of hybrid orbitals when forming certain molecule s disambig ja vi Orbital ... more details
An electron donor is a chemical entity that donates electron s to another compound. It is a reducing agent that, by virtue of its donating electrons, is itself oxidize d in the process. Typical reducing agents undergo permanent chemical alteration through covalent or ionic reaction chemistry. This results in the complete and irreversible transfer of one or more electrons. In many chemical circumstances, however, the transfer of electronic charge to an electron acceptor may be only fractional, meaning an electron is not completely transferred, but results in an electron resonance between the donor ... retain their chemical identities. The electron donating power of a donor molecule is measured by its ionization potential which is the energy required to remove an electron from the highest occupied molecular orbital . The overall energy balance E , i.e., energy gained or lost, in an electron donor acceptor transfer is determined by the difference between the acceptor s electron affinity A and the ionization potential I math Delta E A I , math In chemistry , the class of electron donors that donate not just one, but a set of two paired electrons that form a covalent bond with an electron ... forces for electron donor and acceptor behavior in chemistry is based on the concepts of electropositivity for donors and electronegativity for acceptors of atomic or molecular entities. Electron donors in biology In biology , electron donors release an electron during cellular respiration , resulting in the release of energy . Microorganisms , such as bacteria , obtain energy in the electron ... use. The final result is the electron is donated to an electron acceptor. During this process electron transport chain the electron donor is oxidized and the electron acceptor is reduced. Petroleum hydrocarbons ... compounds are all compounds that can act as electron donors. These reactions are of interest not only ... http toxics.usgs.gov definitions electron donor.html Electron donor definition at United States ... more details
An electron acceptor is a chemical entity that accepts electron s transferred to it from another compound. It is an oxidizing agent that, by virtue of its accepting electrons, is itself redox reduced in the process. ref http toxics.usgs.gov definitions electron acceptor.html ref Typical oxidizing agents undergo permanent chemical alteration through covalent or ionic reaction chemistry, resulting in the complete and irreversible transfer of one or more electrons. In many chemical circumstances, however, the transfer of electronic charge from an electron donor may be only fractional, meaning an electron is not completely transferred, but results in an electron resonance between the donor and acceptor ... their chemical identities. The electron accepting power of an acceptor molecule is measured by its electron affinity which is the energy released when filling the lowest unoccupied molecular orbital LUMO . The overall energy balance E , i.e., energy gained or lost, in an electron donor acceptor transfer is determined by the difference between the acceptor s electron affinity A and the ionization potential I of the electron donor math Delta E A I , math . In chemistry , a class of electron acceptors that acquire not just one, but a set of two paired electrons that form a covalent bond with an electron ... The driving forces for electron donor and acceptor behavior in chemistry is based on the concepts .... Examples Examples of electron acceptors include oxygen , nitrate , iron III , manganese IV , sulfate .... Fact date March 2008 In biology , a terminal electron acceptor is a compound that receives or accepts an electron during cellular respiration or photosynthesis . All organisms obtain energy by transferring electrons from an electron donor to an electron acceptor. During this process electron transport chain the electron acceptor is reduced and the electron donor is oxidized . See also redox ... definitions electron acceptor.html Electron acceptor definition at United States Geological ... more details
Electron optics is a mathematical framework for the calculation of particle paths along given electrostatic ..., deflection, chromatic effects . Electron optics calculations are, besides other uses, needed for electron ... approximation , this can be done using ray transfer matrix analysis . Electron properties main Electron Electrons are charged particles point charge s with rest mass . The electron also has an associated spin physics spin of 1 2. While in motion an electron possesses kinetic energy , regardless of any ... into a screened field free region, which initially imparts the energy required to accelerate the electron. Given sufficient voltage, the electron can be accelerated sufficiently fast to exhibit measurable ... associated wave properties such as wavelength, phase and amplitude. With respect to electron optics, the nature of the electron as a charged particle causes electrons to interact with imposed electron ... of electron optical theory. Field interactions Particle interpretation Magnetic fields interact with an electron in a manner that alters velocity independently of kinetic energy velocity magnitude . Electrons move according to the cross product of the magnetic field and the electron propagation ... radius dependent upon electron velocity and magnetic field strength field strength according ... r is the orbit radius, m is the mass of an electron, v is the electron velocity, e is the charge on the electron ... electrostatic field, an electron will deflect towards the positive gradient of the field ... , a full analysis of electron paths can be obtained by solving Maxwell s equation however in many ... to not only the nucleus, but also the matter s electron charge cloud. Therefore electrons require vacuum to propagate any reasonable distance, such as would be desirable in electron optic ... 90685 3 ref See also Charged particle beam Strong focusing Electron beam technology Electron microscope ... eo.html Air Force Research Laboratory Electron Optics Program refend DEFAULTSORT Electron Optics ... more details
distinguish Visa Debit Refimprove date October 2010 globalize date January 2011 Image Visa Electron card.jpg thumb 250px Norway Norwegian old design Visa Electron card Image Visa Electron.PNG thumb 250px Sweden Swedish Visa Electron card featuring the new Electron logo Visa Electron is a debit card available ... card to the Visa Debit card. The difference between Visa Electron and Visa Debit is that payments with Visa Electron require that all the funds be available at the time of transfer, i.e., Visa Electron ... and aircraft do not support Visa Electron because their systems cannot check for the availability of funds ..., one bank may issue a Visa Electron debit card , while another may issue a credit card . It is most ... countries. This is because Visa Electron cards are also linked to the Visa PLUS interbank network ... s accounts. ref name bbc2 http news.bbc.co.uk 1 hi programmes moneybox 3717331.stm Electron users blocked online BBC News ref As of 2009, most UK banks have migrated away from Visa Electron of the major banks, only HBOS still issues the card ref name Halifax Visa Electron http www.halifax.co.uk bankaccounts other bank accounts easycash Halifax EasyCash Electron Card ref , with others including ... 1 hi business 8384034.stm Visa Electron cards to be phased out BBC News ref Lloyds TSB, Barclays ... cards Visa Electron has become popular with younger people and students. As each transaction requires funds to be checked accounts cannot be overdrawn. Therefore banks will issue a Visa Electron card ... Electron to customers who should not be allowed to go overdrawn, banks will issue what is ostensibly ... as Electron. This can cause these cards to be declined where an actual Visa Debit card would be accepted, for example at petrol pumps or train stations. As Visa Electron cards do not have Embossing ... which surcharge credit and debit card payments do not usually surcharge Visa Electron payments ... cards ref name bbc1 , but neither affords the card a special status any more. In China , Visa Electron ... more details
Electron holography is holography with electron waves. Dennis Gabor invented holography in 1948 ref D. Gabor, A new microscopic principle, Nature 4098, 777 1948 . ref when he tried to improve resolution in electron microscope. The first attempts to perform holography with electron waves were made by Haine and Muley in 1952 ref M. E. Haine, T. Mulvey, The formation of the diffraction image with electrons ... invented biprism for electrons and recording of electron holograms in off axis scheme became possible. Cowley has described 20 configurations for electron holography ref J. M. Cowley, Twenty forms of electron ... i.e. energy spread of electron beam are required to perform holographic measurements. High energy electron holography in off axis scheme Electron holography with high energy electrons 80 200keV can be realized in a transmission electron microscope TEM in off axis scheme. Electron beam is split into two parts by very thin positively charged wire. Positive voltage deflects the electron waves ... in TEM.jpg thumb An illustration to off axis electron holography in transmission electron microscope ... ref M. Lehmann, H. Lichte, Tutorial on off axis electron holography, Microsc. Microanal ... of the object function are reconstructed. Electron holography in in line scheme Original holographic ... electron beam, part of the wave is scattered by the object object wave and it interferes with the unscattered ... by the size of the electron source. Holography with low energy electrons 50 1000eV can be realized ..., Phys. Rev. Lett. 65 10 , 1204 1206 1990 . ref . File InlineHolography.jpg thumb Inline electron ... and sample must be properly grounded and shielded from outside noise. Applications Electron holography ref H. Lichte, Electron holography approaching atomic resolution, Ultramicroscopy 20, 293 1986 . ref ref A. Tonomura, Applications of electron holography, Rev. Mod. Phys. 59, 639 1987 . ref is commonly ... et al., Micros. Res. and Tech. 64, 390 2004 . ref . The principle of electron holography can also ... more details
Electron transfer ET is the process by which an electron moves from an atom or a chemical species e.g. ..., and detoxification. Additionally, the process of energy transfer can be formalized as a two electron .... ISBN 0 12 352651 5. ref but there are now many examples of ET in organic chemistry . Classes of electron transfer There are several classes of electron transfer, defined by the state of the two redox centers and their connectivity Inner sphere electron transfer main Inner sphere electron transfer ..., in which case the electron transfer event is termed intramolecular electron transfer. More ... following the ET event. In such cases, the electron transfer is termed intermolecular electron ... partners. Outer sphere electron transfer main Outer sphere electron transfer In outer sphere ET reactions ..., the electron hops through space from the reducing center to the acceptor. Outer sphere electron transfer ... describes the Degenerate energy level degenerate reaction between permanganate and its one electron ... Mn O sub 4 sub sup sup In general, if electron transfer is faster than ligand substitution, the reaction will follow the outer sphere electron transfer. Often occurs when one both reactants are inert ... work w sub r sub 2. changing bond lengths, reorganize solvent activated complex 3. Electron transfer ... work w sub p sub Heterogeneous electron transfer main Heterogeneous electron transfer In heterogeneous electron transfer, an electron moves between a chemical species and a solid state electrode . Theories addressing heterogeneous electron transfer have applications in electrochemistry and the design ... to address outer sphere electron transfer and was based on a transition state theory approach. The Marcus theory of electron transfer was then extended to include inner sphere electron transfer ... most discussions of electron transfer ever since. Both theories are, however, semiclassical in nature ... of vibronic coupling on electron transfer. In particular the PKS theory of electron transfer ... more details
unreferenced date December 2010 Electron spectroscopy is an analytical technique to study the electronic structure and its dynamics in atom s and molecule s. In general an excitation source such as x ray s, electron s or synchrotron radiation will eject an electron from an inner shell atomic orbital orbital of an atom. Detecting photoelectron s that are ejected by x rays is called x ray photoelectron spectroscopy XPS or electron spectroscopy for chemical analysis ESCA . Detecting electrons that are ejected from higher orbitals to conserve energy during electron transitions is called Auger electron spectroscopy AES . Experimental applications include high resolution measurements on the intensity and angular distributions of emitted electrons as well as on the total and partial ion yields. Ejected electrons can escape only from a depth of approximately 3 nanometers or less, making electron spectroscopy most useful to study surfaces of solid materials. Depth profiling is accomplished by combining an electron spectroscopy with a sputtering source that removes surface layers. Synchrotron radiation research work has been carried out at the MAX Laboratory in Lund, Sweden, Elettra Storage Ring in Trieste, Italy, and at ALS in Berkeley, CA. External links http www.chemistry.adelaide.edu.au external soc rel content e spec.htm The University of Adelaide, Australia http physics.oulu.fi elsp.php?tag top&lang en The University of Oulu, Finland analytical chemistry stub Category Spectroscopy de Elektronenspektroskopie fa hr Elektronska spektroskopija pl Spektroskopia elektronowa ru uk ... more details
Electron Equivalent is a concept commonly used in redox chemistry , reactions involving electron transfer , to define a quantity e.g. energy or moles relative to one electron. Gibbs free energy Energies of formation are often given as kilojoules per electron equivalent to enable calculation of specific reaction energies on a per electron basis. Reactions containing movement of electrons are often balanced such that reaction quantities are given in relation to the transfer of a single electron, allowing quantification of reactants and products in relation to a single electron transfer. References Refbegin cite book last1 Rittman first1 B.E. last2 McCarty first2 P.L. title Environmental Biotechnology Principles and Applications publisher McGraw Hill date 2001 page 60 isbn 0072345535 cite book last1 Schwarzenbach first1 Rene P. last2 Gschwend first2 Philip M. last3 Imboden first3 Dieter title Environmental Organic Chemistry edition 2nd date 2003 isbn 0471357302 publisher John Wiley & Sons page 568 cite book last1 Sayyar first1 Bahareh title Thermodynamic electron equivalent models for Geobacter species publisher University of Toronto Canada date 2008 isbn 0494449144 Refend Category Thermodynamic free energy Category Fundamental physics concepts Category Chemical reactions chemistry stub ... more details
dablink This article is about nuclear physics. For electron capture processes in chemistry, see Electron capture ionization and Electron capture dissociation . See also Beta decay File Elektroneneinfang 2 Phasen .png thumb Electron capture Electron capture is a process in which a proton rich nuclide absorbs an inner atomic electron changing a nuclear proton to a neutron and simultaneously emits a neutrino ... state of the new nuclide. Electron capture is the primary decay mode for isotope s with a relative ... by emitting a positron . Electron capture also exists as a viable decay mode for radioactive ... to allow it, and thus electron capture is the sole decay mode. For example, rubidium 83 37 protons, 46 neutrons will decay to krypton 83 36 protons, 47 neutrons solely by electron capture the energy ... of electron capture, one of the orbital electron s, usually from the K or L electron shell K electron capture , also K capture , or L electron capture , L capture , is captured by a proton in the nucleus, forming a neutron and an electron neutrino . border 0 style height 2em SubatomicParticle link yes Proton SubatomicParticle link yes Electron SubatomicParticle link yes Neutron SubatomicParticle link yes Electron Neutrino Since the proton is changed to a neutron in electron capture, the number of neutrons increases by 1, the number of protons decreases by 1, and the atomic mass number remains unchanged. By changing the number of protons, electron ... in charge, now exists in an energetically excited state with the inner shell missing an electron .... History The theory of electron capture was first discussed by Gian Carlo Wick in a 1934 paper, and then developed by Hideki Yukawa and others. K electron capture was first observed by Luis Alvarez ... Electron Capture by Nuclei, Emilio Segr , chapter 3 in Discovering Alvarez selected works of Luis W ... Accessed on line October 7, 2009. ref ref Nuclear K Electron Capture, Luis W. Alvarez, Physical ... more details
Interventions infobox Name PAGENAME Image Caption ICD10 ICD9unlinked ICD9proc 92.25 MeshID OPS301 OtherCodes Electron therapy or Electron Beam Therapy EBT is a kind of external beam radiotherapy where electrons are directed to a tumor site. Equipment Electron beam therapy is performed using a medical linear accelerator . This device can also be used to produce high energy photon beams. When electrons are required, the x ray target is retracted out of the beam and the electron beam is collimated with a piece of apparatus known as an applicator or an additional collimating insert, constructed from a low melting point alloy. Properties Electron beams have a finite range, after which the dose falls off rapidly. Therefore they spare deeper healthy tissue. The depth of the treatment is selected by the appropriate energy. Indications Electron beam therapy is used in the treatment of superficial tumors like cancer of skin regions, or total skin e.g. mycosis fungoides , diseases of the limbs e.g. melanoma and lymphoma , nodal irradiation, and it may also be used to boost the radiation dose to the surgical bed after mastectomy or lumpectomy . For deeper regions IOERT Intraoperative electron radiation therapy might be applied. References Eric E. Klein Electron Beam Therapy Dosimetry, Planning, and Techniques in Edward C. Halperin, Carlos A. Perez, Luther W. Brady ed. Perez and Brady s Principles and Practice of Radiation Oncology, 5th. edition, 2008 See also Intraoperative Electron Radiation Therapy IOERT IOERT External beam radiotherapy EBRT EBRT Radiation oncology DEFAULTSORT Electron Therapy Category Electron beams in medical applications Category Medical physics Category Radiation oncology ar ... more details
s behalf, Electron later joined the Imperial Guard members in battle against Excalibur comics ... Storm , Electron joined Oracle Marvel Comics Oracle and Flashfire comics Tempest in capturing Rick ... during the Kree Shi ar War. ref Avengers West Coast 80 ref Electron was also among the Imperial Guard members to later lay claim to the devastated Kree Empire after the war. ref Avengers 347 ref Electron ... the conflict. ref Uncanny X Men 480 ref Powers and abilities Electron is a member of the alien race ... hand to hand combatant, trained in armed and unarmed combat by the Shi ar Imperial Guard. Electron has the ability to project electromagnetic energy and move metallic objects. Electron s costume ... had a long run as artist on the Legion . Electron is based on LSH member Cosmic Boy . ref Kaminski, John. Marvunapp http www.marvunapp.com Appendix4 electronimpguard.htm Electron Accessed Apr. 22, 2009. ref References reflist External links http www.marvel.com universe Electron 28alien 29 Electron ... Marvel Comics aliens Category Marvel Comics superheroes tl Electron komiks ... more details
DISPLAYTITLE Electron bird Taxobox name Electron image Electron platyrhynchum Panama 8a.jpg image width 250px image caption Broad billed Motmot regnum Animal ia phylum chordate Chordata classis Aves ordo Coraciiformes familia Motmot idae genus Electron genus authority Johannes Gistel Gistel , 1848 subdivision ranks Species subdivision Keel billed Motmot E. carinatum br Broad billed Motmot E. platyrhynchum Electron is a genus of the motmot s, a family biology family of Neotropics Neotropical near passerine bird s. The genus has two species Keel billed Motmot , Electron carinatum Broad billed Motmot , Electron platyrhynchum Both inhabit humid evergreen tropical forest. Both occur in Central America , and the Broad billed Motmot occurs in a large region of South America as well. They are distinguished from other motmots by their much wider bills. The rackets on their tails are less dramatic than those of many other motmot species and may be absent. The species are very similar except in adult plumage but the adult Keel billed resembles the juvenile Broad billed . A mixed pair apparently courting has been observed Howell and Webb 1995 . The name Electron is a Latin ization of the Ancient Greek word for amber , and can mean bright in scientific names Jaeger 1978 the amber colored eyes of the Keel billed Motmot Howell and Webb 1995 may be the connection. Citation needed date August 2007 The name was given 46 years before an elementary particle was named electron . References Cite book last Howell first Steve N. G. coauthors Webb, Sophie title A Guide to the Birds of Mexico and Northern Central America publisher Oxford University Press pages 439, 790 791 year 1995 isbn 0 19 854012 4 Cite book last Jaeger first Edmund C. authorlink Edmund Jaeger title A Source Book of Biological ... . Accessed 2007 08 17. DEFAULTSORT Electron Bird Category Momotidae Coraciiformes stub ca Electron es Electron ave fr Electron oiseau hu Electron nl Electron geslacht pl Electron ptaki ... more details
Electron diffraction refers to the wave nature of electrons. However, from a technical or practical point ... in this case the incident electron can be described by a wave. For this reason, an electron can be regarded ... ray and neutron diffraction . Electron diffraction is most frequently used in solid state physics and chemistry ... electron microscopy transmission electron microscope TEM , or a scanning electron microscope SEM as electron backscatter diffraction . In these instruments, electrons are accelerated by an electrostatic ... . Apart from the study of crystals i.e. electron crystallography , electron diffraction is also a useful technique to study the short range order of amorphous solids, and the geometry of gas electron ... later for electrons which have a rest mass with the observation of electron diffraction in two independent ... shared the Nobel Prize for Physics in 1937 for their work. Theory Electron interaction with matter ... for electron diffraction, the intensity of a diffracted beam is given by math I mathbf g left ... The wavelength of an electron is given by the wave particle duality de Broglie equation math lambda frac h p math Here math h math is Planck s constant and math p math the relativistic momentum of the electron ... is the mass of the electron, and math e math is the elementary charge.The electron wavelength is then given by math lambda frac h p frac h m 0v frac h sqrt 2m 0eU math However, in an electron microscope, the accelerating potential is usually several thousand volts causing the electron to travel at an appreciable ... of 10,000 volts 10 kV giving an electron velocity approximately 20 of the speed of light, while a typical TEM can operate at 200 kV raising the electron velocity to 70 the speed of light. We therefore need to take relativistic mass relativistic effects into account. It can be shown that the electron ... ray diffraction is in the order of 100 pm Cu k 154 pm . Electron diffraction in a TEM Electron diffraction of solids is usually performed in a Transmission Electron Microscopy Transmission Electron ... more details
The electron liquid is a model system used by physicists to theoretically study interactions among electrons. The uniform electron liquid is a well known model for simple metals like sodium or Aluminum. The ionic charges are assumed to be smudged out to form a uniform static positive background, and the electrons are assumed to move in this positive background which maintains charge neutrality. This is also known as the Jellium model. If the Coulomb interaction between the electrons is neglected, then we have the free electron gas, or the free Fermi gas . However, when the Coulomb interaction is switched on, we have a many body problem of interacting particles. The weakly interacting regime of densities is known as the electron gas. At zero temperature, this happens if the density is very high ... interaction is weak and the free electron gas is a good approximation. Thus the high density regime is known as an electron gas . Perturbation theory can be used in this regime to discuss the properties of weakly interacting electron systems. When math r s math becomes greater than unity, interactions are important and this regime is known as the electron liquid . The electron liquid model holds ... i.e, in low density electron systems , the electron liquid crystallizes forming a crystalline phase known as the Wigner crystal . Perturbation theory fails for electron liquids where math r s 1 math ... electrons thus weakening it , a free electron like model known as the Landau&ndash Fermi liquid theory ... method. Because of Fermi statistics, the electrons in the electron liquid fill up to an energy ... of 12 electron Volts. If the temperature is greater than 12 eV, the electron liquid becomes partially degenerate, since the states above the Fermi energy begin to get occupied. Such electron fluids ..., Many particle Physics Plasmas and finite T electron liquids M. W. C. Dharma wardana, Ed. E. K ..., NY 1993 Category Condensed matter physics Category Electron Liquid Category Article Feedback 5 ... more details
About the quantum mechanical probability density of an electron the number density of electrons in a plasma, also called electron density Plasma physics Merge electronic density date September 2010 Electron density is the measure of the probability of an electron being present at a specific location. In molecule s, regions of electron density are usually found around the atom , and its bonds. In de ... , the electron density covers an entire region, i.e., in benzene they are found above and below ... the electron density is higher next to the single bonds. ref e.g., the white line in the diagram ... as chromophores. In Quantum chemistry quantum chemical calculations , the electron density, ..., File ElectronDensityFormula.PNG center Electron Density Formula Image ElectronDensityAniline.PNG 300px thumb right Electron density calculated for aniline , high density values indicate atom ... on a molecule s shape and size. P is the density matrix . Electron densities are often be rendered ... images of electron density. For example, in aniline see image at right . Graphical models, including electron density are a commonly employed tool in chemistry education. ref cite journal title Teaching Chemistry with Electron Density Models authors Alan J. Shusterman and Gwendolyn P. Shusterman ..., high electron densities are associated with the carbon s and nitrogen , but the hydrogen ... to choose a value for the electron density, often called the IsoValue. Some software ref http ... allows for specification of the electron density in terms of percentage of total electrons enclosed ... of total electrons enclosed, the electron density surface can be used to locate atoms, emphasize electron densities associated with chemical bond s, or to indicate overall molecular size and shape ... pages 61 86 isbn 1 890661 18 X ref Graphically, the electron density surface also serves as a canvas ... of electrostatic potential mapped upon the electron density provides an indicator for charge ... more details
Unreferenced date January 2008 File Egun.jpg thumb 250px right Electron gun from a cathode ray tube File Kathodestraalbuis2.jpg thumb 250px right Electron gun from an oscilloscope CRT An electron gun also called electron emitter is an electrical component that produces an electron beam that has a precise kinetic energy and is most often used in television set s and computer display s which use cathode ray tube CRT technology, as well as in other instruments, such as electron microscope s and particle accelerators . Electron guns may be classified in several ways by the type of electric field generation DC or RF , by emission mechanism thermionic emission thermionic , photocathode , field electron emission cold emission , Plasma physics plasmas source , by focusing pure electrostatic or with magnetic fields , or by the number of electrodes. Characteristics A direct current, electrostatic thermionic electron gun is formed from several parts a hot cathode , which is heated to create a stream of electrons via thermionic emission , electrodes generating an electric field which focus the beam ... where gas enters from one end face, undergoes electron bombardment from the side walls, and is subjected ... color cathode ray tubes such as those used in color television s incorporate three electron guns, each ... primary color s. Applications The most common use of electron guns is in cathode ray tube cathode ray tubes , which were widely used in computer and television monitors. An electron gun can also ... used in mass spectrometry in a process called electron ionization to ionize vaporized or gaseous particles. See also Cathode ray tube Electron microscope Optics Particle accelerators References references External links http electronics.howstuffworks.com question694.htm Howstuffworks.com electron gun http www.fieldp.com cpb.html Charged Particle Beams , free text with material on electron gun design Category Electron beam Category Accelerator physics Category Vacuum tubes ca Can d electrons ... more details
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