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CCMR - RET 2008 WEEK 5

CCMR - RET 2008 WEEK 5. A type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. . SEM (scanning electron microscope). How does SEM work?.

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CCMR - RET 2008 WEEK 5

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  1. CCMR - RET 2008 WEEK 5

  2. A type of electron microscope that images the sample surface by scanning it with a high-energy beam of electrons in a raster scan pattern. SEM (scanning electron microscope)

  3. How does SEM work? • Electron beam interacts with the material, causing a variety of signals to be emitted-revealing details of the material’s shape, homogeneity and elemental composition.

  4. SEM Images • Low accelerating voltages • finer surface structure images can generally be obtained.

  5. SEM Images • High accelerating voltages • the beam penetration and diffusion area become larger, resulting in unnecessary signals being generated from within the specimen.

  6. SEM Images Lichen Unknown

  7. Electron Microprobe 1149 Snee Hall

  8. C.The electrons hit the sample - This knocks out inner electrons in the sample - The atom is now in an excited state. An outer electron drops down to the inner energy level releasing energy in the form of x-rays at the same time. A.Electrons are generated by heating a tungsten filament similar to the one in a light bulb. B.Electrons pass through lenses that condense the beam, remove aberrations and focus the beam E.The reflected rays are then counted and recorded by a detector. D.X-rays are then reflected through a crystal probelab.geo.umn.edu/electron_microprobe.html

  9. Electron Microprobe Uses • Non - destructive • Compositional Analysis • Quantitative • Qualitative • Precise X-Ray intensities • High Spectral Resolution http://www.authorstream.com/Presentation/Janelle-19809-Electron-Beam-MicroAnalysis-Geol-619-1-History-Electrons-as-Entertainment-ppt-powerpoint/

  10. Applications of the Electron Microprobe

  11. Case Study One – What is under the fingernails? Clay?

  12. Paint?

  13. Lichen? SEM image

  14. Insect Wing? SEM image

  15. Electron Microprobe Analysis Since the fingernail is an organic compound, there was a large carbon peak. Other elements such as calcium and sulfur might be found in fingernails normally.

  16. Other Applications of Electron Microprobe

  17. GEOLOGY- Chemical analysis of rocks, dating, plate tectonics

  18. Archeology Compositional distinctions between 16th century ‘fac¸on-de-Venise’ and Venetian glass vessels excavated in Antwerp, Belgium† I. De Raedt,aK. Janssens*a and J. Veeckmanb aDepartment of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium. E-mail: koen@uia.ua.ac.be bExcavation Department of the City of Antwerp, Godefriduskaai 36, B-2000 Antwerp, Belgium Received 29th October 1998, Accepted 10th December 1998 At JEOL 6300 SEM/EDX Based on chemical analysis, 50% of the glassware was from Italy

  19. FORENSIC SCIENCE • SEMGSR The SEM solution for Automated Analysis and Classification of Gunshot Residue SEM/ Microprobe is used to analyze inorganic compounds in gunshot residue

  20. STUDY POTENTIAL ELECTROCATALYSTS FOR FUEL CELLS (Based on lecture by Hector Abruna) Sputter different concentrations of metals onto a substrate

  21. 2. Perform Thermal imaging to determine areas of higher electrochemical activity 3. Use scanning electrochemical microscopy (SECM) to test sample’s ability to oxidize hydrogen/formic acid and reduce oxygen.

  22. Now we need to determine the chemical composition Of the product before bulk manufacture Obtain composition with microprobe and Rutherford backscattering (RBS) SEM-Observe texture and crystal grain size GADDS-Determine crystal structure

  23. Niobium/Tin Film Studies

  24. Unannealed Sample- 2 to 1 Niobium to Tin

  25. Annealed Sample - Large peak seen for Niobium. About 10% of mass unaccounted for. Oxygen accounted the missing mass- the niobium was probably oxidized.

  26. Butterfly Wings -The Sequel-

  27. Light Microscope Images 20µ Butterfly Scales showing overlapping pattern 10µ Individual scales showing ribbing pattern

  28. Light Microscope views 20 µ 10 µ Fringe Scales Tips of Fringe scales

  29. Fringe Scales of Wing 100 µ 50µ Optical Microscope -Transmitted Light Optical Microscope – Reflected Light

  30. Unpolarized vs Polarized Light 10 µ 10µ Wing Scale Unpolarized Light 50x objective lens Wing Scale Polarized Light 50x objective lens

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