2.2 Electron microscopy Flashcards

1
Q

electron microscope

A
  • electron microscope resolves the fine structure of cell
  • biological specimens require special preparation for the EM
  • multiple images combined to increase resolution
  • different views of single object combined - 3D reconstruction
  • specific macromolecules localized by immunogold EM
  • images of surfaces obtained by scanning EM
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2
Q

Transmission electron miscroscope

A
  • tungsten filament
  • negative shield
  • anode accelerates beam
  • magnetic lenses - coil of wire generates strong magnetic field
  • electrons charged particles - deflected
  • vacuum
  • thin + dry specimen
  • static charge -> deflect electrons
  • copper plate - electrical earth
  • monochrome
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3
Q

Scanning electron microscope

A
  • video technology
  • used for dense structures
  • 3D - better solution
  • detector not focus
  • electrical signal generated
  • back-scattered electrons (high energy) - surface shape + nature of specimen
  • secondary electrons (low energy) - escape at top 2 nm surface - shape
  • auger electronsproduced by x-rays - interaction with specimen
  • x-rays emitted - used to identify elements
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