Electron microscope

• Transmission Electron Microscope

  • uses a beam of electrons which have a much shorter wavelength than light
  • can magnify up to 500000 times
  • have excellent resolving power
• Limitations of TEMs

  • living specimens can't be viewed because the system is in a vacuum
  • specimens must be extremely thin
  • specimens are killed and chemically fixed in a time-consuming process
  • method can result in altercations known as artefacts
  • only 2D images are captured
  • image in black and white
• Scanning Electron Microscope

  • electrons are passed across the surface of the specimen
  • scattered electrons form an image on the screen
  • depressions appear dark and extensions appear light
  • image has a three-dimensional appearance
• Artefacts are things that result from the way the specimen is prepared, but not part of the natural specimen
• Limitations and advantages of SEMs

  • only 2D images produced
  • resolving power is lower than TEMs
  • specimens don't need to be thin
  • preparation technique less compex
  • cannot see internal structures