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Topic: Transmission electron microscope

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	Encyclopedia: Transmission electron microscope
		Transmission electron microscopy (TEM) is an imaging technique whereby a beam of electrons is focused onto a specimen causing an enlarged version to appear on a fluorescent screen or layer of photographic film (see electron microscope), or can be detected by a CCD camera.
		Like all matter, electrons have both wave and particle properties (as demonstrated by Louis-Victor de Broglie), and their wave-like properties mean that a beam of electrons can in some circumstances be made to behave like a beam of radiation.
		Electrons are generated by a process known as thermionic discharge in the same manner as the at the cathode in a cathode ray tube, or by field emission; they are then accelerated by an electric field and focussed by electrical and magnetic fields on to the sample.
	www.nationmaster.com /encyclopedia/Transmission-electron-microscope (810 words)

	Resolution of an Electron Microscope
		An electron microscope is an instrument that uses electrons instead of light for the imaging of objects.
		In a TEM, a monochromatic beam of electrons is accelerated through a potential of 40 to 100 kilovolts (kV) and passed through a strong magnetic field that acts as a lens.
		The STM is similar to the TEM except for the fact that it causes an electron beam to scan rapidly over the surface of the sample and yields an image of the topography of the surface.
	hypertextbook.com /facts/2000/IlyaSherman.shtml (634 words)

	Botany online: Microscopy - Electron Microscopy
		The power of resolution of electron microscopy is usually restrained by the quality of the lens-systems and especially by the technique with which the preparation has been achieved.
		The accelerated ray of electrons passes a drill-hole at the bottom of the anode.
		The scanning transmission electron microscope (STEM): In this development of the SEM do the electrons pass through the preparation and the secondary radiation thus generated is used for image formation.
	www.biologie.uni-hamburg.de /b-online/e03/03e.htm (782 words)

	electron on Encyclopedia.com
		It belongs to the lepton class of particles and, together with its antiparticle, the positron, and its associated neutrino and antineutrino, constitutes a subfamily of the leptons.
		Electron microscopy for rapid diagnosis of infectious agents in emergent situations (1).
		Electron Beam Imaging The image is printed by (1) charging the drum, (2) adhering the toner to the drum, (3) tra.
	www.encyclopedia.com /html/e1/electron.asp (912 words)

	What are Electron Microscopes? (Site not responding. Last check: 2007-11-06)
		Electron Microscopes are scientific instruments that use a beam of highly energetic electrons to examine objects on a very fine scale.
		Electron Microscopes were developed due to the limitations of Light Microscopes which are limited by the physics of light to 500x or 1000x magnification and a resolution of 0.2 micrometers.
		The Transmission Electron Microscope (TEM) was the first type of Electron Microscope to be developed and is patterned exactly on the Light Transmission Microscope except that a focused beam of electrons is used instead of light to "see through" the specimen.
	www.unl.edu /CMRAcfem/em.htm (428 words)

	ATOMIC AND MOLECULAR IMAGING WITH THE TRANSMISSION ELECTRON MICROSCOPE
		TEM images of these specimens illustrate the ability of this technology to resolve subunit organization and morphology for high molecular weight proteins, to detect structure of low molecular weight proteins by enhancement of weak phase-contrast information, and to conduct a time-course study of structural changes of a specimen in the electron beam.
		Electron images obtained on the TEM were relayed to a yttrium/aluminum/garnet electron detector and a Gatan unit equipped with a SIT-tube video camera capable of detecting light intensity levels as low as 1 x 10-6 footcandles.
		For TEM observation, the specimens were spread on a formvar-coated copper grid and negatively stained with a 3% solution of methylamine tungstate (Faberge and Oliver, 1974).
	www.botany.utexas.edu /facstaff/facpages/mbrown/ongres/jsharp.htm (2105 words)

	Transmission Electron Microscope (Site not responding. Last check: 2007-11-06)
		The biggest difference is the source of illumination: the light microscope uses a beam of light, the electron microscope uses a beam of electrons, to illuminate the sample.
		In the electron microscope, the lenses are electromagnetic and by changing the electric current to the lenses, it is possible to change the strength of the lens and thereby change the magnification of the image.
		In operation, a beam of electrons is focused to a large spot and transmitted through a thin, stained slice of sample.
	www.sci.sdsu.edu /EM_Facility/tem.html (259 words)

	CMM: Transmission Electron Microscopy (Site not responding. Last check: 2007-11-06)
		Materials for TEM must be specially prepared to thicknesses which allow electrons to transmit through the sample, much like light is transmitted through materials in conventional optical microscopy.
		Because the wavelength of electrons is much smaller than that of light, the optimal resolution attainable for TEM images is many orders of magnitude better than that from a light microscope.
		The energy of the electrons in the TEM determine the relative degree of penetration of electrons in a specific sample, or alternatively, influence the thickness of material from which useful information may be obtained.
	www.uq.edu.au /nanoworld/tem_gen.html (338 words)

	[No title] (Site not responding. Last check: 2007-11-06)
		The electron gun in a scanning electron microscope is the source for the electron beam used to probe the sample.
		Electrons are emitted from a cathode, accelerated by passage through electrical fields and focussed to a first optical image of the source.
		This beam of electrons will be focussed by the shape of the field gradient to a cross-over just before the anode, forming the first optical image of the source and ensuring that a larger percentage of the electrons will pass through the aperture of the anode.
	www.sem.com /analytic/sem.htm (4648 words)

	Two10 Gallery
		In all cases, the microscope works by light being focused by a concave mirror and/or a condenser before it passes through the specimen and into an ‘objective’, which magnifies the subject before it is viewed through the eyepiece.
		The electron beam - generated by electric current through a filament - is accelerated by a high voltage potential and thus can penetrate through the section with limited distortion or absorption; for this the section has to be very thin (typically one ten thousandth of a millimetre) and firmly supported.
		The incident electron beam causes electrons to be emitted from the surface of the subject and it is the pattern of this electron emission that forms the image.
	www.wellcome.ac.uk /en/old/MISexhTWObiaHOW.html (1038 words)

	The Transmission Electron Microscope
		TEMs use electrons as "light source" and their much lower wavelength makes it possible to get a resolution a thousand times better than with a light microscope.
		Instead of glass lenses focusing the light in the light microscope, the TEM uses electromagnetic lenses to focus the electrons into a very thin beam.
		At the bottom of the microscope the unscattered electrons hit a fluorescent screen, which gives rise to a "shadow image" of the specimen with its different parts displayed in varied darkness according to their density.
	www.nobel.se /physics/educational/microscopes/tem/index.html (266 words)

	Dennis McMullan Scanning Microscope
		A breakthrough in the microscopic imaging of surface topography in the TEM was the introduction of replicas by Mahl (1941) and these set the standard for the next 25 years although they were tedious to make and could be subject to serious artefacts.
		The first scanning electron microscope with a sub-micron probe was developed by von Ardenne, a private consultant who had his own laboratory in Berlin, over the very short period of about 2 years; he also had had experience in the development of TV camera tubes (von Ardenne 1985).
		He argued that the incident beam electrons produce secondary electrons at or near the surface from an area approximately equal to the beam diameter and give a high resolution image ("nutzbare Strahlung"); the beam electrons then penetrate the sample and a proportion of them are back-scattered and reach the surface where they produce further secondaries.
	www-g.eng.cam.ac.uk /125/achievements/mcmullan/mcm.htm (5948 words)

	Intro to TEM (Site not responding. Last check: 2007-11-06)
		The transmission electron microscope was first developed in the 1930's after it was apparent the effective role that wavelength has on the theoretical resolution.
		So the great advantage the electron microscope offers over light microscopes, is about a thousand fold increase in resolution and a hundred fold increase in depth of field.
		Electrons are high energy particles which will easily be effected by any mater they encounter.
	nsm1.fullerton.edu /%7Eskarl/EM/Microscopy/IntroTEM.html (535 words)

	Microscope World - Huge selection, low prices, knowledgeable customer support
		Microscopes for coin collecting, stamp collecting, and other hobbies - stereo low power microscopes are generally best for collectors.
		Generally, the objective lenses are very close to the specimen and the specimen is mounted on a microscope slide.
		The microscopes come in a variety of powers from 10x - 80x and are available with a single magnification, dual or zoom magnifications (continuous).
	MicroscopeWorld.com (333 words)

	Electron Microscope and Image Analysis Center
		The Electron Microscope and Image Analysis Center (EMIAC) is located in the School of Natural Sciences at California State University at San Bernardino.
		Lectures on theory of operation of the scanning electron microscope and specimen preparation.
		Lectures on theory of operation of the transmission electron microscope and specimen preparation.
	biology.csusb.edu /electron.htm (610 words)

	Transmission Electron Microscope (Site not responding. Last check: 2007-11-06)
		A projector shines a beam of light through (transmits) the slide, as the light passes through it is affected by the structures and objects on the slide.
		TEMs work the same way except that they shine a beam of electrons (like the light) through the specimen(like the slide).
		The darker areas of the image represent those areas of the sample that fewer electrons were transmitted through (they are thicker or denser).
	www.unl.edu /CMRAcfem/temoptic.htm (476 words)

	Physical equipment: Transmission Electron Microscope
		The JEM-200 CX is a high performance transmission electron microscope.
		The basic instrument is expanded with two additional extensions namely a scanning attachment and a energy dispersive X-ray spectrometer, thus enabling the operator to perform a wide range of measurements.
		Moreover, this microscope provides very stable and excellent bright field - as well as dark field images at low to high magnifications and a variety of electron diffraction patters instantly.
	www.mtm.kuleuven.ac.be /Research/Equipment/Physical/TEM-JEM-200CX.html (141 words)

	CMS—Transmission Electronic Microscopy Capability at LLNL (Site not responding. Last check: 2007-11-06)
		The TEM is a very powerful and versatile instrument that is capable of characterizing the internal structure of a wide variety of materials.
		It is possible to view and record the electron diffraction pattern from selected areas of the specimen as small as ~ 1µm by placing an aperture in the image plane then projecting the diffraction pattern of that image onto the recording plane.
		The primary purpose of electron diffraction techniques is to identify the crystal structure of the materials under investigation.
	www-cms.llnl.gov /s-t/TEM.html (1035 words)

	Appendix: Electron Microscopes
		There are, however, two other microscopes you should have at least a nodding familiarity with since it's likely that in the course of your studies and/or practice you will encounter images made with either the transmission electron microscope or the scanning electron microscope.
		A TEM has condenser and objective lenses, just as the light microscope does; but instead of an ocular, the primary image is passed to an imaging system which is the functional equivalent.
		The TEM, as the name implies, actually relies on the transmission of the beam through the specimen: the direct physical interposition of the specimen into the beam is necessary to produce the image.
	education.vetmed.vt.edu /Curriculum/VM8054/Labs/Lab2/Appendix/ems.htm (1417 words)

	JEOL Transmission electron microscopes (TEM)
		The transmission electron microscope operates on the same basic principles as the light microscope but uses electrons instead of light to illuminate the sample.
		The very short wavelength of accelerated electrons improves the resolution to the order of 0.2 nm (0.0000002 mm) which is a thousand times better than what can be resolved by a light microscope.
		In general we can group the transmission electron microscopes into 4 groups according to the maximum accelerating voltage, which also influences both size and cost.
	www.jeoleuro.com /instr/tem/tem.htm (287 words)

	Bio-Imaging Center (Site not responding. Last check: 2007-11-06)
		Since courses in electron microscopy are generally available only at the graduate level, our students are provided with a unique opportunity to view cellular structure at the molecular level, and from an understanding of molecular structure, to better comprehend biological function/processes.
		In order that the electron beam pass through the specimen, the samples must be cut ultrathin, less than 1/10,000 of a millimeter, using a diamond or glass fracture knife and a precision machine called an ultramicrotome.
		Interaction of the primary electron beam with the specimen surface causes the generation of what are known as secondary electrons (and other energetic phenomena), or the signal.
	www.sunynassau.edu /webpages/biology/becks.htm (1123 words)

	Physics News Update Number 478 - Story THE MOST POWERFUL TRANSMISSION ELECTRON MICROSCOPE (Site not responding. Last check: 2007-11-06)
		In this kind of "field-emission" TEM, electrons are forced out of a cathode and accelerated with the use of a huge voltage and sent toward a sample.
		The voltage used was one million volts, and this produced a beam of electron waves with an intensity (more exactly, brightness) 4 times better than the best previous TEM (or 1000 times larger than conventional thermionic-emission TEMs).
		The voltage has to be held steady at around a million volts with a stability of half a volt; while the electron source must be steady to within 0.5 nm.
	www.aip.org /enews/physnews/2000/split/pnu478-3.htm (217 words)

	Biological Electron Microscope Facility (Site not responding. Last check: 2007-11-06)
		The Biological Electron Microscope Facility (BEMF) at the University of Hawai'i is a multi-user/service facility, administered by the Pacific Biomedical Research Center (PBRC).
		The mission of the BEMF is to provide biological researchers with state-of-the-art electron microscopical instrumentation on a recharge basis.
		The microscope is an upright Nikon Optiphot with a halogen light source, a mercury vapor source for fluorescence, and a krypton/argon laser for its confocal capabilities.
	www.pbrc.hawaii.edu /bemf (923 words)

	TEM promises nanometre-level resolution: News from Hitachi High-Technologies (Electron Microscopy)
		Outstanding spatial resolution at the nanometre level can be achieved on chemical element mapping in the HD-2300 scanning transmission electron microscope from Hitachi High-Technologies.
		In addition to the ability to produce elemental maps at 2nm spatial resolution, the EELS system also has excellent energy resolution, which makes it possible to resolve adjacent peaks that cannot be adequately separated by EDX methods.
		This is because the solid angle for X-ray collection subtended at the EDX detection is 2.5 times greater than that in the TEM, which results in a corresponding increase in sensitivity.
	www.electronicstalk.com /news/hic/hic114.html (429 words)

	TEM in Martinsried
		Electron Microscopy Yellow Pages The purpose of this service is to provide an extensive collection of links related to electron microscopy inside the World Wide Web.
		It is maintained by Pierre-Henri Jouneau at the Center for Electron Microscopy of the "Ecole Polytechnique Fédérale de Lausanne", in Switzerland.
		Microscope 3D Data Base AIM:To provide the scientific community with a searchable volume data base from the microscopes.
	www.biochem.mpg.de /baumeister/TEM/home.html (188 words)

	[No title]
		Pioneering developments of aberration-correcting electron optics have created the unprecedented opportunity to directly observe the atomic-scale order, electronic structure, and dynamics of individual nanoscale structures by advanced transmission electron microscopy.
		The substantial expense of developing and maintaining such aberration-corrected electron microscopes is beyond the ability of individual investigators or even university centers.
		The Department of Energy’s electron beam microcharacterization centers propose to lead the development of advanced aberration corrected electron microscopes in user facilities and provide the necessary infrastructure to make this instrumentation broadly available to the scientific user community.
	ncem.lbl.gov /team3.htm (466 words)

	Transmission Electron Microscope (Site not responding. Last check: 2007-11-06)
		TEM involves the manipulation of an electron beam which passes through a specially prepared ultrathin section of a specimen to obtain a greatly enlarged, high-resolution picture of the specimen's internal structures.
		The vacuum system consists of a differential pump system with turbomolecular pump (170 l/s pumping capacity) and a two-stage rotary ruffing pump (8 m3/h pumping capacity), and provides a working high vacuum of <9x10-7 mbar.
		The system is equipped with an integrated imaging electron energy spectrometer that consists of six lenses and a prism-mirror-prism type spectrometer.
	www.epa.gov /ged/larb/tem.htm (187 words)

	biology - Transmission electron microscopy
		Another type of TEM is the scanning transmission electron microscope (STEM), where the beam can be rastered across the sample to form the image.
		Modern research TEMs may include abberation correctors, to reduce the amount of distortion in the image, allowing information on features on the scale of 0.1nm to be obtained.
		Monochromators may also be used which reduce the energy spread of the incident electron beam to less than 0.15eV.
	www.biologydaily.com /biology/Transmission_electron_microscope (867 words)

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