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Topic: Recombination (physics)

In the News (Mon 16 Nov 09)

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	Physics Myths and physics facts
		Ionosphere: The theory for the physics of the ionosphere is flawed in many respects partially due to the inconsistencies in the underlying theories like atomic physics and plasma physics.
		Paradox: In several areas of physics, especially Quantum Mechanics, apparent paradoxes are used as an argument to justify an irrational, dualistic interpretation of the theory.
		Recombination: Radiative Recombination of ions with electrons is one of the fundamental processes in plasmas and should be treated therefore on an atomistic basis.
	www.physicsmyths.org.uk (8102 words)

	Recombination - Wikipedia, the free encyclopedia
		Recombination usually refers to the biological process of genetic recombination and meiosis, a genetic event that occurs during the formation of sperm and egg cells.
		After the decoupling of matter and radiation, which happened at about the same time as recombination, ambient photons could travel freely, and are visible today as the Cosmic Microwave Background.
		In physics, Lord Kelvin's Knot theory describes atoms as knots of swirling vortices in the æther.
	en.wikipedia.org /wiki/Recombination (283 words)

	How Does The Vibrational Motion Of Molecular Ions Influence Its Recombination With Free Electrons?
		Dissociative recombination, a process where a molecular ion captures a free electron and breaks into fragments, is one of the most important processes in various ionized gas environments such as laboratory plasmas, planetary ionospheres and interstellar molecular clouds.
		The main obstacle in the study of molecular recombination processes is the fact that when molecular ions are produced in laboratory, their internal energy (which is usually described as vibrational and rotational energy) can be very high, while the molecular ions present in planetary ionospheres and interstellar clouds in contrast have very little internal energy.
		Since the dissociative recombination process is known to be very sensitive to the internal energy, the experimental studies of this reaction were hampered by the difficulty to produce large amounts of internally cold molecular ions; direct comparisons with theoretical calculations were basically impossible.
	www.eurekalert.org /pub_releases/1998-07/M-HDTV-020798.php (701 words)

	Quintessence (November 2000) - Physics World - PhysicsWeb
		The relationship between the physical size and the apparent angular size as observed on the sky depends crucially on the geometry of the space-time.
		Whatever physical processes created the initial energy in the universe had to arrange for an exponentially large difference between the two forms of energy, but somehow this difference had to have exactly the right value for the vacuum energy to become important 15 billion years later.
		Robert R Caldwell is in the Department of Physics and Astronomy, Dartmouth College, 6127 Wilder Laboratory, Hanover, New Hampshire 03755-3528, USA (www.dartmouth.edu/artsci/physics/faculty/Caldwell.html).
	physicsweb.org /article/world/13/11/8 (5482 words)

	Physics Today News Picks: Education Archives
		Oak Ridger: The number of college students enrolled in undergraduate health physics programs continues to increase, according to a survey of the 30 U.S. universities with health physics programs conducted by Oak Ridge Institute for Science and Education.
		The Guardian: The study of physics in UK schools and universities is spiraling into decline as many teenagers believe it is too difficult, says a report from the University of Buckingham.
		Network World: Institutions of higher education are up in arms over an FCC ruling on wiretapping they say could cost them billions of dollars in upgrades, expose their networks to more attacks, and jeopardize rights to privacy and freedom of speech.
	blogs.physicstoday.org /newspicks/education (3567 words)

	Carrier generation and recombination - Wikipedia, the free encyclopedia
		In the solid state physics of semiconductors, carrier generation and recombination are processes by which mobile electrons and electron holes are created and eliminated.
		Carrier generation and recombination processes are fundamental to the operation of many optoelectronic semiconductor devices, such as photodiodes, LEDs and laser diodes.
		During radiative recombination, a form of spontaneous emission, a photon is emitted with the wavelength corresponding to the energy released.
	en.wikipedia.org /wiki/Recombination_(physics) (742 words)

	Physics Today May 2001
		The nonvanishing angular momentum of quantum rings in the presence of a magnetic field is closely related to the fascinating physics of the so-called persistent currents in mesoscopic rings.
		This field of atomic physics and quantum optics has shown, for example, that spontaneous emission of radiation from excited atoms can be greatly enhanced or inhibited by placing the atoms in a specially designed cavity or between mirrors.
		Axel Lorke is a professor in the Laboratory for Solid-State Physics at Gerhard-Mercator University in Duisburg, Germany.
	www.physicstoday.org /pt/vol-54/iss-5/p46.html (3213 words)

	Ultracold plasmas come of age (March 2001) - Physics World - PhysicsWeb
		These atoms are presumably the result of three-body recombination in which two electrons and an ion collide to leave one of the electrons bound in a Rydberg state, while the other electron takes away the binding energy.
		The physical basis of this recombination is not yet fully understood.
		A rethinking of traditional collisional models is required because, at such low temperatures, the ions hardly move at all on the timescale of the ionization and recombination processes.
	physicsweb.org /article/world/14/3/3 (1456 words)

	Ionospheres (Site not responding. Last check: 2007-11-02)
		Distinct ionospheric regions develop because (a) the solar spectrum deposits its energy at various heights depending on the absorption characteristics of the atmosphere, (b) the physics of recombination depends on the density, and (c) the composition of the atmosphere changes with height.
		Thus the four main ionospheric regions can be associated with different governing physical processes, and this physics (rather than simple height differentiation) is the basis for labeling an ionospheric region on another planet as a D, E, F1, or F2 region.
		Recombination of molecular ions as in Fl; but limiting process here is charge transfer, giving an attachment-like recombination law.
	utd500.utdallas.edu /~coley/ionospheres.html (981 words)

	WFU Physics Seminars
		Prior to Recombination, the Universe was completely ionized and photons, the cosmic background radiation (CBR), interacted strongly with the ionized matter.
		At Recombination, electrons and protons combined to form neutral hydrogen and the Universe evolved to a mostly neutral state.
		Measurements of the CMB are therefore direct probes of the state of the early Universe at Recombination.
	www.wfu.edu /academics/physics/seminars/2002_Fall/stancil.html (285 words)

	University of Denver - Physics and Astronomy
		My research is in the area of granular particle physics and the compaction of granular materials.
		This effort is both experimental and theoretical and involves balloon-borne experiments studying the particles directly, their composition and energy spectra seen at the top of the atmosphere, and indirectly through the gamma-ray and other radiations they produce as they interact with gas and magnetic fields in the galaxy.
		My research area includes: application of Monte Carlo methods to physics and engineering problems and optimization algorithm, advanced nuclear fuel cycle and reactor concepts, transmutation of nuclear waste and plutonium disposition, including minimization and stabilization of nuclear waste using shock compaction technologies, nuclear technology for space application, reactor core physics and radiation protection design.
	www.physics.du.edu /community.cfm?type=faculty (1228 words)

	Session gTuaI1 - Magnetic Confinement: Divertors, MHD.
		It is important primarily because the recombined atoms are not accelerated through the sheath - thus reducing divertor plate sputtering, and because most of the potential energy of recombination (13.6 eV) is released as radiation before the ion strikes the plate.
		The experimental evidence for recombination is found in the deuterium emission spectra from the divertor, in particular in the Balmer- and/or Lyman-series.
		The spectra show that the dominant recombination mechanism is 3-body recombination into excited states of deuterium and that the populations of the atomic levels with n\gtapprox3 are dominated by recombination, rather than by excitation.
	flux.aps.org /meetings/YR97/BAPSDPP97/abs/S2000.html (1660 words)

	Experimental Surface Physics and Astrophysics Research (Site not responding. Last check: 2007-11-02)
		The importance of knowing how hydrogen recombination occurs stems from the fact that hydrogen assumes very important roles in the interstellar medium (ISM), from shielding the core of an interstellar cloud from UV radiation and hastening its collapse, to presiding to the chemistry of virtually every molecule formed in space.
		In our laboratory we set-up an apparatus to study hydrogen recombination reactions on surfaces of materials under conditions that are made as close as technically possible to the conditions prevalent in the interstellar medium.
		The excitement that has characterized research in condensed matter physics in recent years is due to discoveries of phenomena occurring at surfaces.
	www-hl.syr.edu /depts/Physics/ESPAResearch.htm (914 words)

	[No title]
		For a recombination rate slow compared to the visible light switching frequency, (B), the infrared oscillations never saturate, and the net amplitude is much smaller.
		Such defects are known to reduce the recombination lifetime due to the creation of mid-gap states.
		The differences in the two higher frequency images are primarily caused by remnants of the recombination process still visible in the image at the lower of the two frequencies.
	www.physics.ncsu.edu /optics/carrlife/carrimage.html (637 words)

	BJT base recombination current
		I thought that the base recombination current (say in a pnp bjt) was the current caused by the electrons that come up the base wire to compensate the loss of free electrons from the recombination process in the base.
		I still am not sure what the base recombination current is (meaning the second term in the right-hand side of the equation 5.2.13).
		Recombination current in general is defined as current that occurs
	www.physicsforums.com /showthread.php?t=120809 (379 words)

	Atomic Physics,Fysikum
		This enhancement depends among other things on the external electromagnetic fields, on the polarization of the laser light and on the energy distribution of the electrons as seen from the frame of reference of the ions.
		Dielectronic recombination is an electron-ion recombination mechanism where recombination occurs simultaneously with the excitation of the core of the ionic state.
		This process is resonant and leaves the ion in a doubly-excited state that must be radiatively stabilized by the emission of a succession of photons.
	www.atom.physto.se /~web/laser.html (1542 words)

	Nuclear Physics Seminar Abstract (Site not responding. Last check: 2007-11-02)
		Parton recombination models have been very successful in explaining data taken at RHIC on hadron spectra, nuclear modification factors and elliptic flow emission patterns in Au+Au collisions at transverse momenta above 2 GeV/c, which have exhibited features which could not be understood in the framework of basic perturbative QCD.
		I will show how these observables can be addressed by the recombination approach through incorporating two-particle correlations into the quark distributions which are used as initial condition for the calculation.
		Addressing these topics is essential for extending the recombination approach to a hadronization model for the bulk of the matter created at RHIC.
	www.physics.ohio-state.edu /~ntg/seminars/100705.html (165 words)

	Plasma Physics and Astrophysics Research Papers and Proposals
		Expressions are derived for the atomic cross sections concerning the resonant scattering, photo-ionization and radiative recombination processes under full consideration of the quantum-mechanical boundary conditions for a resonant oscillator (for both the one-dimensional as well as the two-dimensional case which is relevant for circular polarization and/or magnetic fields).
		The resultant recombination cross section for electrons and protons turns out to be several orders of magnitudes larger than values found in the literature (FIG.1).
		The scattering coefficient of highly excited atomic levels formed by recombination from a plasma and energetically broadened by plasma field fluctuations is determined.
	www.plasmaphysics.org.uk /research (6598 words)

	Recombination in Semiconductors (Site not responding. Last check: 2007-11-02)
		Recombination reduces the efficiency by allowing excited electrons to return to the ground state before escaping the cell.
		We study the recombination process to explore this loss mechanism and how it can be minimized.
		The first paper below describes a recombination investigation that reveals new details in the energy level distribution of a semiconductor.
	webphysics.davidson.edu /faculty/thg/Recombination.htm (133 words)

	Theoretical Principles of Plasma Physics and Atomic Physics
		Collision Frequency: The concept of a collision frequency is probably the most important one in plasma physics (and the physics of gases in general) when it comes to assessing the significance of the individual physical processes.
		For free-bound transitions this enhancement does not occur and the intensity of the corresponding recombination radiation is directly determined by the plasma density and the associated Radiative Recombination rate into the atomic levels.
		For the calculation of the density of atomic levels populated by recombination, it is important that Radiative Recombination has to be described as a two-step process (see /research/levschem.htm), i.e.
	www.plasmaphysics.org.uk (7930 words)

	The Origin of the 3 K Radiation
		It is recalled that one of the most fundamental laws of physics leads to the prediction that all matter emits electromagnetic radiation.
		It is well known in basic physics and chemistry that atomic hydrogen H is quite unstable.
		We know that the recombination of a proton and an electron is a two-body recombination just as in the case of binding two atomic hydrogen atoms H forming H
	www.newtonphysics.on.ca /COSMIC/Cosmic.html (2268 words)

	School of Physics: People-->Professor:Raymond Flannery
		He is a Fellow of the American Physical Society, a Fellow and Chartered Physicist of the Institute of Physics, London and an Honorary Member of the Royal Irish Academy.
		Theoretical Physics: Atomic and Molecular Physics, Atomic and Molecular Processes in Ionized Gases, Three-Body Recombination at thermal and Ultracold energies, Anti-hydrogen formation, Cold Collisions, Rydberg Plasmas, Collisional Stark Mixing, Classical-Quantal Dynamical Correspondences.
		It was established in 2000 "for recognition of distinguished achievement in Atomic, Molecular, Optical and Plasma Physics." The prize, in honor of the scientific achievements of David Robert Bates is awarded every two years.
	www.physics.gatech.edu /people/faculty/flannery (1324 words)

	Nuclear, atomic and molecular physics and sustainable development: an issue within CEPAMOQ
		In this context, to talk about nuclear, atomic and molecular physics and sustainable development is surprising, all the more given that the former suffers from a negative perception associated with the military use of nuclear energy.
		These problems, little known to the public, are at the core of the research activities of Centre for Atomic Molecular Physics and Quantum Optics (CEPAMOQ) created within the Faculty of Science of the University of Douala on December 17, 1999 by the Cameroon Minister of Higher Education.
		Research of a theoretical nature is oriented towards fundamental studies of atomic physics (life times of heavy radioactive ions including highly ionised lanthanides, atoms in intense laser fields, electron-atom scattering), molecular physics (dissociative recombination of molecular ions, molecules in intense laser field), cluster physics (stability of highly charged metallic clusters).
	www.europhysicsnews.com /full/25/article6/article6.html (1018 words)

	plasma
		However, cross sections for recombination are not generally calculated by the atomic physics community; photoionization cross sections are.
		Radiative recombination gives rise to a continuum of emission, with a minimum energy equal to the binding energy of the ion in its final state.
		Therefore, when asking if recombination to a given level will be important we can examine only the case of zero-energy electrons, where the emitted photon's energy comes entirely from the binding energy of the level.
	cxc.harvard.edu /atomdb/physics/plasma/plasma.html (2790 words)

	Physics of Nonneutral Plasmas (Site not responding. Last check: 2007-11-02)
		To avoid recombination through subsequent electron-ion collisions, the neutral plasma must be hot or dilute or short-lived, or supplied with a lot of energy to encourage continuing ionization.
		However if the species can be spatially separated, the opportunity for recombination is removed, and the resulting nonneutral plasma can be made cold and dense and long-lived, with very little coupling to its environment.
		There is an interesting relation between the physics of intense beams and the physics of non-neutral plasmas.
	www.physics.indiana.edu /~pollock/nnpphysics.html (360 words)

	OSU Physics: Calendar of Events
		Description: Quark recombination is a very successful phenomenological model to understand hadron production from a deconfined quark and gluon phase in high energy nuclear collisions.
		In this talk I review our current understanding of quark recombination and how it might help to make the case for the quark gluon plasma at RHIC.
		I will also discuss some novel directions: recombination beyond the valence quark approximation and jet-like correlations of hadrons.
	www.physics.ohio-state.edu /calendar/event.php3?id=1050 (70 words)

	Tuzemen (Site not responding. Last check: 2007-11-02)
		Tüzemen is Dean of the Faculty of Arts and Sciences and Professor of Physics at Atatürk University in Erzurum, Turkey.
		Therefore, recombination types and mechanisms play important roles in the quantum efficiency and other characteristics of the devices.
		It is also important that recombination centers are uniformly distributed across wafers where the devices are constructed.
	www.wfu.edu /physics/news/f2000/tuzeman/tuzeman.html (309 words)

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