- Field ion microscope
Field ion microscopy (FIM) is an analytical technique used in
materials science. The field ion microscope is a type of microscopethat can be used to image the arrangement of atoms at the surface of a sharp metal tip.It was the first technique by which individual atoms could be spatially resolved. The technique was pioneered by Erwin Müller. Images of atomic structures of tungstenwere first published in 1951 in the journal "Zeitschrift für Physik".
In FIM, a sharp (<50 nm tip radius) metal tip is produced and placed in an
ultra high vacuumchamber, which is backfilled with an imaging gas such as heliumor neon. The tip is cooled to cryogenic temperatures (20–100 K). A positive voltageof 5000 to 10000 volts is applied to the tip. Gas atoms adsorbed on the tip are ionized by the strong electric fieldin the vicinity of the tip (thus, "field ionization"), becoming positively charged and being repelled from the tip. The curvature of the surface near the tip causes a natural magnification — ions are repelled in a direction roughly perpendicular to the surface (a "point projection" effect). A detector is placed so as to collect these repelled ions; the image formed from all the collected ions can be of sufficient resolution to image individual atoms on the tip surface.
Unlike conventional microscopes, where the spatial resolution is limited by the wavelength of the particles which are used for imaging, the FIM is a projection type microscope with atomic resolution and an approximate magnification of a few million times.
Field emission microscope
List of surface analysis methods
* [http://arc.nucapt.northwestern.edu/ Northwestern University Center for Atom-Probe Tomography]
* [http://www.aip.org/png/2006/264.htm Photograph of tungsten needle tip imaged through FIM]
Wikimedia Foundation. 2010.
Look at other dictionaries:
field-ion microscope — /feeld uy euhn, uy on/ a device in which the atomic structure of the surface of a conductor is made visible by introducing helium gas into the device and applying a high voltage to ionize and accelerate the gas toward a fluorescent screen. Cf.… … Useful english dictionary
field ion microscope — noun : a high magnification microscope in which an image of the atoms of a metal surface is formed on a fluorescent screen by means of usually helium ions formed in a high voltage electric field • field ion microscopy noun … Useful english dictionary
field-ion microscope — /feeld uy euhn, uy on/ a device in which the atomic structure of the surface of a conductor is made visible by introducing helium gas into the device and applying a high voltage to ionize and accelerate the gas toward a fluorescent screen. Cf.… … Universalium
field ion microscope — Type of microscopy in which the specimen is illuminated with ions, often gallium ions, that are focused electrostatically. The ions remove components of the specimen, lower atomic masses first. These are imaged and provide information on… … Dictionary of molecular biology
field-ion microscope — Смотри автоионный микроскоп (ионный проектор) … Энциклопедический словарь по металлургии
field ion microscope — Erwin W Mueller … Inventors, Inventions
field-emission microscope — noun electron microscope used to observe the surface structure of a solid • Hypernyms: ↑electron microscope * * * /feeld i mish euhn/ a device in which electrons liberated by field emission are accelerated toward a fluorescent screen to form a… … Useful english dictionary
field-emission microscope — /feeld i mish euhn/ a device in which electrons liberated by field emission are accelerated toward a fluorescent screen to form a magnified image of the emitting surface. Cf. field ion microscope. [1950 55] * * * … Universalium
ion microscope — ion microscope, = field ion microscope. (Cf. ↑field ion microscope) … Useful english dictionary
field ion microscopy — noun see field ion microscope … Useful english dictionary