what are electron microscopes

8/9/2019 What Are Electron Microscopes

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Electron Microscope

What are Electron Microscopes?

Electron Microscopes are scientific instruments that use a

beam of highly energetic electrons to examine objects on a very fine scale. Thisexamination can yield the following information:

1)TopographyThe surface features of an object or "how it looks", its texture; direct relation between

these features and materials properties (hardness, reflectivity...etc.)

2)MorphologyThe shape and size of the particles making up the object; direct relation between these

structures and materials properties (ductility, strength, reactivity...etc.)

3)Composition

The elements and compounds that the object is composed of and the relative amounts of

them; direct relationship between composition and materials properties (melting point,reactivity, hardness...etc.)

4)Crystallographic Information

How the atoms are arranged in the object; direct relation between these arrangements andmaterials properties (conductivity, electrical properties, strength...etc.)

Where did Electron Microscopes Come From?

Electron Microscopes were developed due to the limitations

of Light Microscopes which are limited by the physics of light to 500x or 1000xmagnification and a resolution of 0.2 micrometers. In the early 1930's this theoretical

limit had been reached and there was a scientific desire to see the fine details of the

interior structures of organic cells (nucleus, mitochondria...etc.). This required 10,000xplus magnification which was just not possible using Light Microscopes.

The Transmission Electron Microscope (TEM) was the first

type of Electron Microscope to be developed and is patterned exactly on the LightTransmission Microscope except that a focused beam of electrons is used instead of light

to "see through" the specimen. It was developed by Max Knoll and Ernst Ruska inGermany in 1931.

The first Scanning Electron Microscope (SEM) debuted in

1942 with the first commercial instruments around 1965. Its late development was due to

the electronics involved in "scanning" the beam of electrons across the sample. An

Farooq K.P AlFalah

English Medium High School


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Electron Microscope

excellent article was just published in Scanningdetailing the history of SEMs and I would

encourage those interested to read it.

How do Electron Microscopes Work?

Electron Microscopes(EMs) function exactly as their optical

counterparts except that they use a focused beam of electrons instead of light to "image"

the specimen and gain information as to its structure and composition.The basic steps involved in all EMs:

1. A stream of electrons is formed (by the Electron Source) and accelerated toward the

specimen using a positive electrical potential2. This stream is confined and focused using metal apertures and magneticlenses into a thin,

focused, monochromatic beam.

3. This beam is focused onto the sample using a magnetic lens

4. Interactions occur inside the irradiated sample, affecting the electron beam

These interactions and effects are detected and transformed

into an image. The above steps are carried out in all EMs regardless of type.

Farooq K.P AlFalah

http://www.unl.edu/CMRAcfem/gun.htmhttp://www.unl.edu/CMRAcfem/glossary.htm#aperturehttp://www.unl.edu/CMRAcfem/glossary.htm#lenshttp://www.unl.edu/CMRAcfem/glossary.htm#lenshttp://www.unl.edu/CMRAcfem/glossary.htm#monochromatichttp://www.unl.edu/CMRAcfem/interact.htmhttp://www.unl.edu/CMRAcfem/glossary.htm#aperturehttp://www.unl.edu/CMRAcfem/glossary.htm#lenshttp://www.unl.edu/CMRAcfem/glossary.htm#monochromatichttp://www.unl.edu/CMRAcfem/interact.htmhttp://www.unl.edu/CMRAcfem/gun.htm


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Electron Microscope

Electron microscope

An electron microscope is a type ofmicroscope thatproduces an electronically-magnified image of a specimen for detailed observation. The electron

microscope (EM) uses aparticle beam ofelectrons to illuminate the specimen and create amagnified image of it. The microscope has a greaterresolving powerthan a light-powered optical

microscope, because it uses electrons that have wavelengths about 100,000 times shorter than

visible light (photons), and can achieve magnifications of up to 1,000,000x, whereas lightmicroscopes are limited to 2000x magnification.

The electron microscope uses electrostatic and

electromagnetic "lenses" to control the electron beam and focus it to form an image. These lenses

are analogous to, but different from the glass lenses of an optical microscope that form a

magnified image by focusing light on or through the specimen.

Electron microscopes are used to observe a wide range

of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy

samples, metals, and crystals. Industrially, the electron microscope is primarily used for qualitycontrol and failure analysis in semiconductor device fabrication.

History

In 1931, the German physicist Ernst Ruska and Germanelectrical engineerMax Knoll constructed theprototype electron microscope, capable of four-

hundred-power magnification; the apparatus was a practical application of the principles ofelectron microscopy. Two years later, in 1933, Ruska built an electron microscope that exceededthe resolution attainable with an optical (lens) microscope. Moreover, Reinhold Rudenberg, the

scientific director ofSiemens-Schuckertwerke, obtained the patent for the electron microscope in

May of 1931. Family illness compelled the electrical engineer to devise an electrostaticmicroscope, because he wanted to make visible thepoliomyelitis virus.

In 1937, the Siemens company financed the

development work of Ernst Ruska and Bodo von Borries, and employed Helmut Ruska (Ernsts

brother) to develop applications for the microscope, especially with biologic specimens. Also in1937, Manfred von Ardenne pioneered the scanning electron microscope. The firstpractical

electron microscope was constructed in 1938, at the University of Toronto, by Eli FranklinBurton and students Cecil Hall, James Hillier, and Albert Prebus; and Siemens produced the firstcommercialTransmission Electron Microscope (TEM) in 1939. Although contemporary electron

microscopes are capable of two million-power magnification, as scientific instruments, they

remain based upon Ruskasprototype.

Farooq K.P AlFalah

http://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Particle_beamhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Angular_resolutionhttp://en.wikipedia.org/wiki/Optical_microscopehttp://en.wikipedia.org/wiki/Optical_microscopehttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Magnificationhttp://en.wikipedia.org/wiki/Electrostatic_lenshttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Microorganismshttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Biopsyhttp://en.wikipedia.org/wiki/Metalshttp://en.wikipedia.org/wiki/Crystallinehttp://en.wikipedia.org/wiki/Semiconductor_device_fabricationhttp://en.wikipedia.org/wiki/Ernst_Ruskahttp://en.wikipedia.org/wiki/Max_Knollhttp://en.wikipedia.org/wiki/Prototypehttp://en.wikipedia.org/wiki/Reinhold_Rudenberghttp://en.wikipedia.org/wiki/Siemens-Schuckertwerkehttp://en.wikipedia.org/wiki/Poliomyelitishttp://en.wikipedia.org/w/index.php?title=Bodo_von_Borries&action=edit&redlink=1http://en.wikipedia.org/wiki/Helmut_Ruskahttp://en.wikipedia.org/wiki/Manfred_von_Ardennehttp://en.wikipedia.org/wiki/Scanning_electron_microscopehttp://en.wikipedia.org/wiki/University_of_Torontohttp://en.wikipedia.org/wiki/Eli_Franklin_Burtonhttp://en.wikipedia.org/wiki/Eli_Franklin_Burtonhttp://en.wikipedia.org/wiki/James_Hillierhttp://en.wikipedia.org/wiki/Prototypehttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Particle_beamhttp://en.wikipedia.org/wiki/Electronhttp://en.wikipedia.org/wiki/Angular_resolutionhttp://en.wikipedia.org/wiki/Optical_microscopehttp://en.wikipedia.org/wiki/Optical_microscopehttp://en.wikipedia.org/wiki/Photonhttp://en.wikipedia.org/wiki/Magnificationhttp://en.wikipedia.org/wiki/Electrostatic_lenshttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Microorganismshttp://en.wikipedia.org/wiki/Cell_(biology)http://en.wikipedia.org/wiki/Moleculeshttp://en.wikipedia.org/wiki/Biopsyhttp://en.wikipedia.org/wiki/Metalshttp://en.wikipedia.org/wiki/Crystallinehttp://en.wikipedia.org/wiki/Semiconductor_device_fabricationhttp://en.wikipedia.org/wiki/Ernst_Ruskahttp://en.wikipedia.org/wiki/Max_Knollhttp://en.wikipedia.org/wiki/Prototypehttp://en.wikipedia.org/wiki/Reinhold_Rudenberghttp://en.wikipedia.org/wiki/Siemens-Schuckertwerkehttp://en.wikipedia.org/wiki/Poliomyelitishttp://en.wikipedia.org/w/index.php?title=Bodo_von_Borries&action=edit&redlink=1http://en.wikipedia.org/wiki/Helmut_Ruskahttp://en.wikipedia.org/wiki/Manfred_von_Ardennehttp://en.wikipedia.org/wiki/Scanning_electron_microscopehttp://en.wikipedia.org/wiki/University_of_Torontohttp://en.wikipedia.org/wiki/Eli_Franklin_Burtonhttp://en.wikipedia.org/wiki/Eli_Franklin_Burtonhttp://en.wikipedia.org/wiki/James_Hillierhttp://en.wikipedia.org/wiki/Prototype


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Electron Microscope

Applications:

1) Semiconductor and data storage Circuit edit

Defect analysis

Failure analysis

2) Biology and life sciences

Diagnostic electron microscopy

Cryobiology

Protein localization

Electron tomography

Cellular tomography Cryo-electron microscopy Toxicology

Biological production and viral load monitoring

Particle analysis

Pharmaceutical QC

Structural biology

3D tissue imaging

Virology

Vitrification

3) Industry

High-resolution imaging

2D & 3D micro-characterization Macro sample to nanometer metrology

Particle detection and characterization

Direct beam-writing fabrication

Dynamic materials experiments

Sample preparation

Forensics

Mining (mineral liberation analysis)

Chemical/Petrochemical

Farooq K.P AlFalah

http://en.wikipedia.org/wiki/Failure_analysishttp://en.wikipedia.org/wiki/Diagnostic_electron_microscopyhttp://en.wikipedia.org/wiki/Cryobiologyhttp://en.wikipedia.org/wiki/Electron_tomographyhttp://en.wikipedia.org/w/index.php?title=Cellular_tomography&action=edit&redlink=1http://en.wikipedia.org/wiki/Cryo-electron_microscopyhttp://en.wikipedia.org/wiki/Toxicologyhttp://en.wikipedia.org/w/index.php?title=Biological_production&action=edit&redlink=1http://en.wikipedia.org/wiki/Viral_loadhttp://en.wikipedia.org/wiki/Structural_biologyhttp://en.wikipedia.org/wiki/Virologyhttp://en.wikipedia.org/wiki/Forensicshttp://en.wikipedia.org/wiki/Mininghttp://en.wikipedia.org/wiki/Chemicalhttp://en.wikipedia.org/wiki/Petrochemicalhttp://en.wikipedia.org/wiki/Failure_analysishttp://en.wikipedia.org/wiki/Diagnostic_electron_microscopyhttp://en.wikipedia.org/wiki/Cryobiologyhttp://en.wikipedia.org/wiki/Electron_tomographyhttp://en.wikipedia.org/w/index.php?title=Cellular_tomography&action=edit&redlink=1http://en.wikipedia.org/wiki/Cryo-electron_microscopyhttp://en.wikipedia.org/wiki/Toxicologyhttp://en.wikipedia.org/w/index.php?title=Biological_production&action=edit&redlink=1http://en.wikipedia.org/wiki/Viral_loadhttp://en.wikipedia.org/wiki/Structural_biologyhttp://en.wikipedia.org/wiki/Virologyhttp://en.wikipedia.org/wiki/Forensicshttp://en.wikipedia.org/wiki/Mininghttp://en.wikipedia.org/wiki/Chemicalhttp://en.wikipedia.org/wiki/Petrochemical

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