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What is a Transmission Electron Microscope (TEM)?

A transmission electron microscope (TEM) generates a beam of electrons which is transmitted through an ultra-thin (~50 nm) sample. Some regions of the sample will let the electrons go through, while others will not. The electrons passing through the specimen are focused into an image that forms onto a fluorescent screen where it can be viewed and recorded with a CCD camera or photographic film. The image consists of shades of grey, with darker features corresponding to regions of the sample that have absorbed the electrons from the beam.

Spatial resolution is how close two features can be within an image and be recorded as distinct. The best spatial resolution (~0.5 nm) of TEM far surpasses that of light microscopes (200 nm); and therefore the TEM reveals features of samples that light microscopes cannot reveal.

TEM’s tungsten filament is the electron emission source and a high tension source that strips the electrons from the filament. The electrons then travels through the column under high vacuum. Attached to the column is a port to insert the sample into the electron beam. Attached to the specimen port are control knobs to move the sample in the beam path. Electromagnetic lenses focus the electron beam and electrostatic plates allow the operator to guide the beam as required. Photographic film or CCD devices are used to record the image from the electrons passing through the sample.

The TEM is used by biologist to investigate cellular features that are not visible by light microscopy, such as ribosomes and small vesicles. Materials scientists use the TEM to probe the fine architectures of materials such as nanoparticles.

Major Features of the Jeol JEM-1200 EX II

  • Tungsten filament and high tension operating between 40 and 120 kV

  • Magnification range: 50X-500,0000X

  • Maximum resolution under optimal condition: 0.35 nm

  • Images can be recorded with an AMT (Advanced Microscopy Techniques Corp.) CCD digital camera

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Last Updated: 9/26/14