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

Introduction Scanning Electron Microscope (Zeiss Supra-25 SEM) History Instrumentation Theory Samples Results & Different Uses Image Capture Elemental Analysis Elemental Mapping A Image: http://www.physics.montana.edu/ical/instrumentation/fesem.html

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 Image: https://www.vonardenne.biz/en/company/manfred-von-ardenne/

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) Image: http://nau.edu/cefns/labs/electron-microprobe/glg-510-class-notes/instrumentation/

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= 0.0276𝑥𝐴𝑥 𝐸 1.67 𝜌 𝑥 𝑍 0.89 Image: http://nau.edu/cefns/labs/electron-microprobe/glg-510-class-notes/instrumentation/

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

Samples B

Samples C

Samples C

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

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