1. Scanning Electron Microscopy
Oddný Þorbergsdóttir, Oddný Ragnarsdóttir, and Linda Hancock A

2. Introduction Scanning Electron Microscope (Zeiss Supra-25 SEM) History
Instrumentation
Theory
Samples
Results & Different Uses
Image Capture
Elemental Analysis
Elemental Mapping A
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3. SEM: Brief History History
First SEM was built by Manfred von Ardenne in Germany in 1937
First SEM sold commercially 1965 (Cambridge Scientific Instrument Co.)
First SEM in Iceland 1988 (NMI)
The one we used: 2004 A
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4. Instrumentation Electron Gun Sample Stage Samples under high vacuum
Camera & Detectors
Focus the Sample
X-ray detector
A: X-ray detector must be a certain distance form the sample (Working distance)
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5. Instrumentation: Interaction Volume
Depth & Width of the Interaction Volume
𝐷= 0.1𝑥 𝐸 1.5 𝜌
B= 0.077𝑥 𝐸 1.5 𝜌
B: Where D/B are in um; E is in kV; p is in g/cc; These are empirical formulas (determined experimentally) higher A, smaller volume
Distance the electron penetrates the sample
r= 𝑥𝐴𝑥 𝐸 𝜌 𝑥 𝑍 0.89
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6. Samples MUST be conductive Preferably flat & non-porous
Powders, etc. prepared in a conductive Bakelite casting & polished
If not conducting, must be coated with gold (imaging only)
Cannot use liquids
B: Conduction improves the signal & reduces thermal damage/charging effects

7. Samples B

8. Samples C

9. Samples C

10. Samples: Elemental Mapping
Backscattered e detector is used for mapping
Bes are more abundant
Provides a higher resolution
Higher Atomic #=more Bes
Because higher e density C

11. Thank You for Listening
We hope this presentation provided you with information on the applications of the theory discussed in class C