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Topic: Scanning tunneling microscope


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  Scanning tunneling microscope - Wikipedia, the free encyclopedia
The scanning tunneling microscope (not to be confused with scanning electron microscopes), STM, was invented in 1981 by Gerd Binnig and Heinrich Rohrer of IBM's Zurich Lab in Zurich, Switzerland.
The STM is a non-optical microscope which employs principles of quantum mechanics.
By scanning the tip over the surface and measuring the height (which is directly related to the voltage applied to the piezo element), one can thus reconstruct the surface structure of the material under study.
en.wikipedia.org /wiki/Scanning_tunneling_microscope   (510 words)

  
 scanning tunneling microscope on Encyclopedia.com   (Site not responding. Last check: 2007-11-06)
SCANNING TUNNELING MICROSCOPE [scanning tunneling microscope] device for studying and imaging individual atoms on the surfaces of materials.
The underlying principle of the microscope is the tunneling of electrons between the sharp tip of a probe and the surface of the sample under study.
Scanning the surface: from gold atoms to benzene molecules, the scanning tunneling microscope probes the intricate structure of surfaces.
www.encyclopedia.com /html/s/scanning.asp   (298 words)

  
 Scanning tunneling microscope
The scanning tunneling microscope is a high-resolution non-optical microscope which employs principles of quantum mechanics.
It is even possible to move and position individual atoms, which makes the scanning tunneling microscope an important tool in nanotechnology.
The scanning tunneling microscope was developed at IBM Zürich in 1981 by Gerd Binnig[?] and Heinrich Rohrer[?] who shared the Nobel Prize in physics in 1986 for the achievement.
www.ebroadcast.com.au /lookup/encyclopedia/te/TEM.html   (166 words)

  
 Scanning tunneling microscopy   (Site not responding. Last check: 2007-11-06)
Scanning tunneling microscopy is a microscopical technique that allows the investigation of electrically conducting surfaces down to the atomic scale.
The reason for the extreme magnification capabilities of the STM down to the atomic scale is mainly the physical properties of the tunneling current.
The tunneling current flows across the small gap that separates the tip from the sample, a case that is forbidden in classical physics but that can be explained by the better approach of quantum mechanics.
www.physnet.uni-hamburg.de /home/vms/pascal/stm.htm   (425 words)

  
 IAP/TU Wien STM Gallery: The Scanning Tunneling Microscope   (Site not responding. Last check: 2007-11-06)
Scanning tunneling microscopy is a technique developed in the eighties and allows imaging solid surfaces with unprecedented resolution.
The operation of a scanning tunneling microscope (STM) is based on the so-called tunneling current, which starts to flow when a sharp tip approaches a conducting surface at a distance of approximately one nanometer.
Thereby, the electronics of the STM system control the tip position in such a way that the tunneling current and, hence, the tip-surface distance is kept constant, while at the same time scanning a small area of the sample surface.
www.iap.tuwien.ac.at /www/surface/STM_Gallery/stm_schematic.html   (491 words)

  
 Scanning Tunneling Microscope
The scanning tunneling microscope (STM) is widely used in both industrial and fundamental research to obtain atomic-scale images of metal surfaces.
STM image, 7 nm x 7 nm, of a single zig-zag chain of Cs atoms (red) on the GaAs(110) surface (blue).
STM image, 35 nm x 35 nm, of single substitutional Cr impurities (small bumps) in the Fe(001) surface.
physics.nist.gov /GenInt/STM/stm.html   (191 words)

  
 Dr. Frank Endres: Nanoscale probes at the interface electrode / electrolyte in Ionic Liquids   (Site not responding. Last check: 2007-11-06)
The tunneling current is strongly dependent on the distance (d) and is a function of the density of states of tip D(tip) and sample D(sample).
The STM can be run in 2 modes of operation: in one mode the tip is scanned over the sample with a constant height and the tunneling current is detected.
STM pictures are always acquired as follows: the tip performs a fast scan in the x-direction and the signals are acquired.
home.eplus-online.de /endres/the_scanning_tunneling_microscope.html   (1905 words)

  
 Scanning Tunneling Microscope
Scanning Tunneling Microscope (STM), a device designed to image conducting surfaces of materials with atomic precision.
The basic element of the STM is a sharp tip made of wolfram, platinum, iridium, or some other conducting material.
Since the tunneling current decreases approximately exponentially with the tip-surface separation, the tip has to be extremely close to the surface in order to record the current, which is typically given in nanoampere units.
nanoatlas.ifs.hr /scanning_tunneling_microscope.html   (411 words)

  
 Principle of Scanning Probe Microscopy
The tunneling current depends so strongly on the distance that it is dominated by the contribution flowing between the last atom of the tip and the nearest atom in the specimen.
In the Interface Physics Group, Scanning Tunneling Microscopy is used to investigate the structure and dynamic behavior of metal surfaces.
In the high-pressure STM experiments we investigate the influence of high pressures of reactive gas mixtures on the structure of metal surfaces, and the resulting effects on the catalytic activity of these metals.
www.physics.leidenuniv.nl /sections/cm/ip/group/Principle_of_SPM.htm   (2730 words)

  
 IBM Archives: Scanning Tunneling Microscope
This is a small-scale version of the Scanning Tunneling Microscope (STM), invented by IBM researchers to produce images of individual atoms and the forces bonding them for the first time.
In scanning tunneling microscopy, a voltage is applied between a surface and a probe so sharp that its tip is a single atom.
As the probe is moved to within a few atomic diameters of a surface, a "tunneling" current flows between the surface and the probe.
www-03.ibm.com /ibm/history/exhibits/vintage/vintage_4506VV3182.html   (142 words)

  
 Scanning tunneling microscope at opensource encyclopedia   (Site not responding. Last check: 2007-11-06)
A scanning tunneling microscope (STM) is used to obtain atomic-scale images of metal surfaces.
The STM is a high-resolution non-optical microscope which employs principles of quantum mechanics.
Depending on the voltage and its characteristics electrons will "tunnel" (this is a quantum-mechanical effect) from the probe to the surface (or vice-versa depending on the polarity,) resulting in a weak electric current.
www.wiki.tatet.com /Scanning_Tunneling_Microscope.html   (249 words)

  
 Scanning Tunneling Microscope   (Site not responding. Last check: 2007-11-06)
Scanning probe microscopes are increasingly able to do more than report on one property of the specimen as a function of position (like the piezo-height at which current between STM tip and specimen is held at some set-point value).
Thus modern "atomic force" microscopes can map lateral force and conductivity along with height, and image-pairs from an air-based STM scanning to and fro can be used to map friction coefficient along with height.
Thus the scanning tunneling microscope, and its other scanned probe cousins, are serving as the vehicle for an increasingly wider range of explorations which take place in worlds on the size scale of atoms and molecules.
www.umsl.edu /~fraundor/stm97x.html   (1465 words)

  
 scanning tunneling microscope
The underlying principle of the microscope is the
Heinrich Rohrer - Heinrich Rohrer Born: 1933 Birthplace: Bucs, Switzerland Scanning tunneling microscope—Binnig...
Gerd Karl Binnig - Gerd Karl Binnig Born: 1947 Birthplace: Frankfurt, Germany Scanning tunneling...
www.infoplease.com /ce6/sci/A0843875.html   (283 words)

  
 Scanning Tunneling Microscope
The heart of the STM is a fine metal wire, called the STM tip, placed in close proximity to a conducting surface as diagrammed in Fig.
The tunneling current is exponentially dependent on the junction width and increases by a decade per Angstrom as the tip is brought closer to the surface.
In typical scanning modes the current is kept constant and the perpendicular tip deflection needed to keep the current fixed is monitored as the tip is moved laterally along the surface.
www.physics.berkeley.edu /research/crommie/research_stm.html   (470 words)

  
 Define scanning tunneling microscope - a Whatis.com definition - see also: STM   (Site not responding. Last check: 2007-11-06)
A scanning tunneling microscope (STM) is a device that obtains images of the atoms on the surfaces of materials.
The STM is not an optical microscope; instead, it works by detecting electrical forces with a probe that tapers down to a point only a single atom across.
The probe in the STM sweeps across the surface of which an image is to be obtained.
searchsmb.techtarget.com /sDefinition/0,,sid44_gci812057,00.html   (248 words)

  
 Science News: Microsketching an underwater surface - scanning tunneling microscope
The microscope may also be useful in electrochemistry for detecting surface changes that occur at electrodes.
Meanwhile, IBM and Stanford University scientists have modified a scanning tunneling microscope to map forces on the surfaces of both conducting and insulating materials.
This new device, called an atomic force microscope, has a diamond tip mounted on a tiny gold-foil spring, which is sandwiched between a sample and a microscope needle's tip.
www.findarticles.com /p/articles/mi_m1200/is_v129/ai_4211082   (641 words)

  
 Integrating a Scanning Tunneling Microscope into a Scanning Electron Microscope
The STM has to be connected rigidly to the SEM to ensure a good resolution of the SEM.
The tunneling current in the STM is affected by the electron beam.
The SEM should always be operated at currents lower than the tunneling current, unless the STM is not in the tunneling regime.
wwwex.physik.uni-ulm.de /lehre/physikalischeelektronik/phys_elektr/node244.html   (335 words)

  
 STM - Scanning Tunneling Microscope
A Scanning Tunneling Microscope is a device which is capable of atomic resolution, and was the subject of a Nobel Prize for IBM researchers who first demonstrated the operating principle in the early 1980s.
In particular, it is often required to alter the temperature of the sample, and ensure an ultra-high vacuum to maintain atomic-level cleanliness of the sample surface.
The first of these was a variable-temperature STM, incorporating both a cryostat and a sample heater to enable the temperature to be varied from 20K to 1000K.
www.tech-enterprise.com /stm.htm   (299 words)

  
 Modified scanning tunneling microscope
Their superconducting behavior begins when about 10 percent of the electrons have been removed, but for over a decade physicists have been puzzled by what happens when somewhat fewer electrons are removed: the material conducts electricity, but just barely, and in theory it shouldn't conduct at all.
An STM uses a needle so fine that its tip consists of just one atom, scanning across a small surface and measuring current flow between the surface and the tip.
For these experiments, it scans a sample and reads the probability that electrons are in certain locations, based on current flow through the STM tip.
www.news.cornell.edu /Chronicle/04/8.26.04/STM_lab.html   (822 words)

  
 High-Speed, Variable-Temperature Scanning Tunneling Microscope
The technical aspects of this microscope are described in [1,2,3,4].
The high speed of the STM is obtained by a combination of fast analog electronics and a fast digital control system, which is interfaced to an ensemble of three T800-transputers and a Silicon Graphics workstation.
A central tube scanner is used to scan the sample surface (pink).
www.physics.leidenuniv.nl /sections/cm/ip/projects/thermo/VTSTM/welcome.htm   (470 words)

  
 Freshman Seminar: Building a Scanning Tunneling Microscope
The aim of this seminar is to teach students who are considering careers in science or engineering the skills necessary to build a complicated piece of scientific equipment from start to finish.
Small groups of 3-4 students will be given guidance to build a scanning tunneling microscope from simple materials.
The scanning tunneling microscope (STM), which earned its 1982 inventors the 1986 Nobel Prize in Physics, was the first tool which allowed scientists to "see" individual atoms.
hoffman.physics.harvard.edu /course.php   (279 words)

  
 Ming the Mechanic: Build Your Own Scanning Tunneling Microscope   (Site not responding. Last check: 2007-11-06)
A group at University of Münster in Germany are giving away the complete DIY plans for building your own Scanning Tunneling Microscope.
While granting the right to build the microscope we make it mandatory that new developments, improvements or other applications of our design are also made openly available for private or educational purposes.
But if it was that particular tunneling microscope you want to build it sounds like those folks in Münster would be happy to help.
ming.tv /flemming2.php?did=10&vid=10&xmode=show_article&amode=standard&aoffset=0&artid=000010-001026&time=1073607401   (324 words)

  
 Scanning Tunneling Microscope   (Site not responding. Last check: 2007-11-06)
This rapid change of tunneling current with distance results in atomic resolution if the tip is scanned over the surface to produce an image.
Russell D. Young, of the National Bureau of Standards, was the first person to combine the detection of this tunneling current with a scanning device in order to obtain information about the nature of metal surfaces.
The instrument which he developed between 1965 and 1971, the Topografiner, altered the separation between the tip and the surface (z) so that, at constant voltage, the tunneling current (or, at constant current, the tunneling voltage) remained constant as the tip was scanned over the surface.
physics.nist.gov /GenInt/STM/text.html   (374 words)

  
 Invent Now | Hall of Fame | Search | Inventor Profile
The most recent revolution came with Heinrich Rohrer and Gerd Karl Binnig's scanning tunneling microscope (STM), invented in 1981, which provided the first images of individual atoms on the surfaces of materials.
The STM can image atomic details as tiny as 1/25th the diameter of a typical atom, which corresponds to a resolution several orders of magnitude better than the best electron microscope.
The STM's significance was quickly recognized throughout the world, and it has been used in fields as diverse as semiconductor science, metallurgy, electrochemistry, and molecular biology.
www.invent.org /hall_of_fame/1_1_6_detail.asp?vInventorID=14   (242 words)

  
 J. Maps STM   (Site not responding. Last check: 2007-11-06)
A scanning tunneling microscope (STM) provides a way to examine surfaces with atomic resolution.
The STM operates by scanning a sharp probe - usually the tip of a sharpened wire - over the surface to be studied.
By rastering the tip over the surface and recording the variations in the tunneling current due to variations in the surface height, a map of the surface can be produced.
www.d.umn.edu /~jmaps/stm1.html   (266 words)

  
 Howstuffworks "How Atoms Work"
However, in 1981, a type of microscope called a scanning tunneling microscope (STM) was developed.
The STM tip moves over the atomic contour of the surface, using tunneling current as a sensitive detector of atomic position.
STM image (7 nm x 7 nm) of a single zigzag chain of cesium atoms (red) on a gallium-arsenside surface (blue)
www.howstuffworks.com /atom9.htm   (455 words)

  
 ☞ reference - Scanning Tunneling Microscope   (Site not responding. Last check: 2007-11-06)
Scanning Tunneling Microscope - Gerd Binnig and Heinrich Rohrer
Gerd Karl Binnig and Heinrich Rohrer are the inventors of the scanning tunneling microscope or STM which provided...
Artist's renderings of a scanning tunneling microscope (STM).
www.reference-site.info /scanningtunnelingmicroscope   (409 words)

  
 Scanning tunneling microscope. (from microscope) --  Britannica Student Encyclopedia
A new technique, called scanning tunneling microscopy, uses a metal probe to scan the topography of a substance, tracing out the hills and spaces that correspond to the surface atoms and the spaces between them.
When a vacuum is created between the probe and specimen and a voltage is applied to the probe, the result is the tunneling of electrons from the probe to the...
The first scientists to use microscopes were able to discover the causes and cures of many diseases.
www.britannica.com /ebi/article-204633   (584 words)

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