SCANNING ELECTRON MICROSCOPE

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 SCANNING ELECTRON MICROSCOPE

  • It is used for the surface characterization of materials.
  • It produces images of a sample by scanning the surface with a focused beam of electrons.
  • It provides information about topography(surface features), morphology (shape and size), composition, and crystallographic information.

PRINCIPLE

The electrons interact with the atoms in the sample, producing various signals that contain information about the surface topography and composition of the sample. 

The accelerated electrons in an SEM carry significant amounts of kinetic energy, and this energy is dissipated as a variety of signals produced by electron sample interactions.

Backscatter electrons are incidental electrons reflected backward which provide composition data related to element and compound detection. Diffracted backscatter electrons determine crystalline structures as well as the orientation of minerals and micro-fabric, X-rays emitted from beneath the sample surface, can provide element and mineral information. SEM produces black and white, 3D images.

WORKING

A beam of electrons is produced in an electron gun, and it passes down the column and onto a series of electromagnetic lenses. These lenses are tubes, wrapped in oil and referred to as solenoids. The coils are adjusted to focus the incident electron beam onto the sample.

ADVANTAGES

  • 3D images,
  • very fast and easy to operate,
  •  Data is available in digital form.

DISADVANTAGES

Expensive and large, training is required, Radiation

APPLICATIONS

  • Essential research tool in life science, biology, medical and forensic science, and metallurgy.
  • In material science for research, quality control.
  • To characterize nanowires, accurate measurement of the composition of semiconductors.
  • For criminal and other forensic investigations.
  • For geological sampling to determine weathering processes and morphology of the samples.


Location: United States

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