3.2 the electron microscope Flashcards
1
Q
principles for TEM
A
- electrons pass through specimen
- denser parts absorb more electrons
- so denser parts appear darker
- short wavelength so higher resolution
2
Q
limitations of TEM
A
- in a vacuum
- very thin specimen
- artefacts present
- in 2D
- complex staining process
3
Q
principles of SEM
A
- short wavelength so high resolution
- electrons are passed back and forth onto the surface
- electrons scattered by surface
4
Q
limitations of SEM
A
- lower resolving power than TEM
- in a vacuum
- not in colour
- complex staining process
5
Q
principles of light microscope
A
- long wavelength so low resolution
- uses beams of light
6
Q
limitations of light microscope
A
- poor resolving power
- uses light which has a longer wavelength
7
Q
what is the resolving power of SEM?
A
20nm
8
Q
what is the resolving power of TEM?
A
0.1m
9
Q
what is the resolving power of light microscopes?
A
200nm
