1. SEM microscope By: Doug, Holly & Oleg

2. Advantages Continuously variable magnification High resolution Depth of focus Elemental analysis attachments Disadvantages Cost More knobs Vacuum Sample limitations Scanning Electron Microscopevs.Optical Microscope

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

4. 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

5. Topographic contrast surface same penetration depth shorter exit distance, higher signal longer exit distance, lower signal

6. SEM general info

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

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

9. SEM general info • Vacuum pump 4 minutes • Turn on filament current & accelerating voltage • Fiddle with the knobs

10. Quenched from 1700 degF Anneal to 900 degF Furnace cooled from 1700 degF Low C steel High C steel Unknown C steel Sample Prep

11. High C (optical 600x) High C (SEM 400x) High C (SEM 3000x)

12. Low C (600x optical) Low C (SEM 400x) Low C (SEM 3000x)

13. Unknown (optical 600x) Unknown C (SEM 400x) Unknown (SEM 3000x)

14. Low C vs High C (SEM 200x) Low Carbon Plastic High Carbon

15. Low C(3000x vs 10000x)