SEM Practice 2

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Author:
saitclt
ID:
184593
Filename:
SEM Practice 2
Updated:
2012-11-20 00:51:08
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INST390SAITCLT2
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SEM
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  1. Resolution
    smallest separation at which two points can be seen as distinct entities
  2. _______ the d-value, the better the resolution
    smaller
  3. If the sample is not transparent, can it still be detected under SEM?
    Yes, because SEM only scans the surface through using electrons not photon
  4. what is the electron source in SEM?
    Tungsten Filament
  5. Where is scanning Coils located?
    located in optical column
  6. How does diffusion pump work?
    • Electric heater heats oil and oil vapour rises up the chimney
    • Vapor is condensed in chimney by cooling coils and it takes air molecules from the top of the pump to the bottom
  7. Can Diffusion pump used directly?
    No, First Mechanical pump has to be used until the pressure gets to 10-2  , then Diffusion pump can be used
  8. Primary Electron ( used for flat surfaces) gives _________  while secondary electron gives__________ about the sample
    • atomic number
    • Surface information
  9. What is Electrical Bias?
    Electrical field which bends the electron towards the detector
  10. Column maintained at _______ vaccum, and sample chamber at ______- vaccume
    • High
    • Low
  11. Wet sample ( non-conductive) can be observed using SE and BSE detection. (T/F)
    True. 
  12. What element is used for cooling SEM?
    Liquid Nitrogen
  13. Depth of field
    extent of the focus through the depth of the image
  14. Accelerating Voltage
    Speed the electron running down the column (KV)
  15. working Distanec
    Distance between aperture and sample
  16. Beam current
    How big of spot we are hitting on the sample
  17. What parameters causes an increase in resolution?
    • Increase accelerating voltage(KV)
    • Lowering working distance
    • smaller aperture size
    • lower the beam current

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