The document discusses the principles and functionalities of scanning electron microscopy (SEM), emphasizing the difference between resolution and magnification. It covers the components of SEM, including the electron source, lenses, and detectors, as well as the imaging and analysis processes involved in examining samples. Key features such as signal generation, backscattered and secondary electrons, and x-ray analysis for material characterization are also outlined.

2. Resolution
• The ability to determine two separate points as singular distinguished
entities
• Resolution ≠ Magnification
• Dependence on wavelength of

4. Magification

7. Scanning Electron Microscope
(simplified drawing)
sample
tungsten filament (electron source)
electrostatic lens (F = qE)
accelerating voltage anode
electromagnetic lenses (F = q v x B)
(condenser lenses)
electromagnetic lens (objective lens)
& deflector coils (raster scan)
e-
detector (scintillator & PMT)
SE

9. SEM General info
• Load the sample into the SEM

10. SEM General info
•Mount the sample on the holder
•“Paint” the conductive path

12. Signal Generation
In (Probe)
• Focused mono-energetic electron beam
Out (Signal)
Imaging
• Backscattered electrons
• Secondary electrons
Analysis
• X-rays
Characteristic x-rays
Bremsstrahlung x-rays (background “noise”)
• Auger electrons

13. x-rays
composition
backscattered e's
microstructure
secondary e's
microstructure
elastically scattered e's
crystallographic structure
inelastically scattered e's
composition
transmitted e's
microstructure
SIGNALS IN ELECTRON MICROSCOPY

14. SEM - scanning electron microscopy
Electron gun
Electron emitter

16. Pearlite structure in steel

17. Austempered ductile iron – fracture surface

20. THANKS