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Glossary terms about Electron

Electrons are elementary particles, found in all atoms, that are grouped in shells around the nuclei of the atoms.

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38 pages mention Electron

Additional material
Links Physics behind electron Microscopy  
The beam travels from the electron gun at the top through the sample and down to the viewing screen. 
Applications and practical uses - what the TEM can do
The transmission electron microscope (TEM) is used to examine the structure, composition, and properties of specimens in submicron detail. 
This occurs when the electrons sense a non-uniform magnetic field as they spiral around the optic axis. 
Background information - What is transmission electron microscopy?
A transmission electron microscope (TEM) is an analytical tool allowing visualisation and analysis of specimens in the realms of microspace (1 micron/1μm = 10-6m) to nanospace (1 nanometer/nm = 10-9m). 
Camera length
Once an accurately calibrated diffraction pattern is achieved, the information in the pattern is used to determine lattice planes and in the indexation of diffraction patterns [see useful links for information on how to index diffraction patterns]. The images are convergent beam electron diffraction patterns (CBED) from a ZnO crystal. 
Chromatic aberration
The term chromatic aberration is related to the energy of the electrons. 
Combining images
Concepts - introduction
The fundamental basis of electron microscopy is the use of an electron beam. 
One of the most common detectors seen on a transmission electron microscope is the x-ray energy dispersive spectroscopy (EDS or EDX) system. 
Diffraction basics
This is because a crystal lattice acts as a diffraction grating: interference patterns are produced in the electron beam as it travels out from the lattice and these can be projected as an image of regular dots or rings. 
Diffraction patterns
When the electron beam interacts with the sample when the sample is oriented with a zone axis pattern parallel to the electron beam, then the diffraction pattern form in the back focal plane of the objective lens is a regular array of reflections. 
Electron column
The electron column is made up of the gun assembly at the top, a column filled with a set of electromagnetic lenses, the sample port and airlock, and a set of apertures that can be moved in and out of the path of the beam. 
Electron gun
The electron gun generates the electron beam. 
Frequently asked questions
Image appearance
This can occur for one of two reasons: Strongly diffracting regions of crystals can appear darker because there are fewer electrons transmitted along the primary beam. 
Image formation basics
The TEM images are formed in two stages: Stage A is the scattering of an incident electron beam by a specimen. 
Image types
Some areas of the sample scatter or absorb electrons and therefore appear darker. 
Images from electrons
electron images from the TEM can be used to achieve different information, for example for morphological, crystallographic or compositional studies. 
Imaging mode setup
There are a number of concepts that need to be mastered when setting up the electron column for suitable imaging modalities. 
Introduction - aims and learning outcomes
Welcome to the online learning module for transmission electron microscopy. 
Kikuchi Patterns
Bragg scattering, that is diffraction of inelastically scattered electrons, can lead to the formation of pairs of parallel lines in the diffraction pattern called Kikuchi lines. 
Lenses: electromagnetic lenses
Machine operating procedures
The following provide examples of the actual steps used in one electron microscope laboratory for some TEMs. 
Magnetic lens system
Within the column the electromagnetic lenses shape the electron beam, which travels in a spiral trajectory. 
Parts of the machine
The typical transmission electron microscope laboratory contains a machine with these components:  
Pole-pieces and Coils
a pole-piece: a cylindrically symmetrical core of soft iron with a hole drilled through it (bore) a coil of copper wire which surrounds each pole-piece. 
Problems with lenses: aberrations
Spherical and chromatic aberrations limit the resolution of conventional electron microscopes. 
Specimen/sample chamber
The cable is plugged into the column to enable electronically-controlled tilting of the holder and therefore the sample. 
Spherical aberration
The further off-axis the electron is, the more strongly it is bent back toward the axis. 
The diffracted beam
When the electron beam passes through the thin crystalline sample, it is diffracted by the atomic planes in the sample when the Bragg condition is satisfied. 
The electron wavelength
The appearance of a diffraction pattern will depend on the orientation of the specimen to the electron beam. 
Transmission electron microscopy in practice
Virtual transmission electron microscopy  
Using the JEM-1010 Transmission Electron Microscope for physical science material
Using the JEM-1010 Transmission Electron Microscope for thin resin sections of biological material
What the TEM can't do
electrons cannot readily penetrate sections much thicker than 200nm.