Electron microscopy
 
Thickness of EM Samples
- Practical Electron Microscopy and Database -
- An Online Book -
Microanalysis | EM Book                                                                                   http://www.globalsino.com/EM/        


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Table 1217. Thickness dependence of electron scattering from a specimen in EM (electron microscope) measurements.
Scattering direction
EM method
Scattering event/angle
Scattering direction
Electrons
Wave (phase) property
Electron property
Contrast interpretation
Thin specimen TEM Less scattering events and then smaller scattering angle
Forward scattering More electrons Strong coherent signal Strong wave property Easy

Back scattering Fewer electrons Weak incoherent signal Weak particle property  
Thick specimen TEM/SEM   Forward scattering Fewer electrons Weak coherent signal Weak wave property Middle
Electron is scattered more than once (plural scattering), and then scattering angle is greater Back scattering More electrons Strong incoherent signal Strong particle property  
Very thick or bulk specimen SEM More scattering events and then greater scattering angle Forward scattering Fewest electrons Weakest coherent signal Weakest wave property Difficult
Electron is scattered >20 times (multiple scattering), and then scattering angle is greatest Back scattering Most electrons Strongest incoherent signal Strongest particle property  

 

 

 

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