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
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
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