Scanning electron microscope (SEM)

Definition

A scanning electron microscope (SEM) is a type of electron microscope that produces high-resolution, three-dimensional images by scanning the surface of a specimen with a focused beam of electrons. SEMs are particularly useful in studying surface structures and morphology at the micro and nano scale.

5 Must Know Facts For Your Next Test

1. SEMs use electrons instead of light to form an image, allowing for much higher resolution than light microscopes.
2. The beam of electrons in an SEM interacts with the atoms on the surface of the sample, producing signals that contain information about the sample's surface topography and composition.
3. Specimens often need to be coated with a thin layer of conductive material, such as gold or platinum, to prevent charging under the electron beam.
4. SEMs can magnify images up to several hundred thousand times, making them essential tools for detailed analysis in microbiology.
5. Unlike transmission electron microscopes (TEM), SEMs provide detailed three-dimensional images but do not offer as high resolution as TEMs.

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Related terms

Transmission Electron Microscope (TEM):

An electron microscope that transmits a beam of electrons through a specimen to form highly detailed two-dimensional images.

Light Microscope: A microscope that uses visible light passed through lenses to magnify small objects.

Electron Beam: A stream of electrons used in various types of microscopes to interact with samples for imaging purposes.