Ge 116 Module 1: Scanning Electron Microscopy

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Ge 116 Module 1 Scanning Electron Microscopy

• Part 2 EDS X-ray analysis and EBSD

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Continuum X-rays
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Characteristic X-rays
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Characteristic X-rays
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Characteristic X-rays
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X-ray counting EDS and WDS
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X-ray counting EDS and WDS
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X-ray counting EDS and WDS
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Energy-Dispersive X-ray Spectrum
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Energy-Dispersive X-ray Spectrum
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Complexities in X-ray production

• Production, ?(?z)

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Complexities in X-ray production

• Absorption

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Complexities in X-ray production

• Absorption

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Complexities in X-ray production

• Secondary Fluorescence

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Complexities in X-ray production

• Secondary Fluorescence

100 ?m
From Milman-Barris et al. (2008)
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Complexities in X-ray production

• Quantitative analysis requires correction for
  production, absorption, and fluorescence effects
• Physics-based methods ZAF, ?(?z)
• Empirical method Bence-Albee
• Correction depends on composition, which is not
  known a priori, so quantification is an iterative
  procedure
• Accurate analysis requires appropriate standards,
  as we will see when we learn electron probe
  analysis

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EBSD
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EBSD configuration
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Diffraction Bragg Equation

• where n is an integer, ? is the wavelength of the
  electrons, d is the spacing of the diffracting
  planes, and ? is the angle of incidence of the
  electrons on the diffracting plane
• Constructive interference between reflections off
  successive planes of charge in the lattice
  requires difference in path length to be an
  integer multiple of the wavelength.

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Aside X-ray Diffraction

• X-ray diffraction is usually done with a
  plane-wave X-ray source
• For monochromatic X-radiation and a single
  crystal, this gives a distribution of points of
  constructive interference around the sphere.
• For monochromatic X-radiation and a powdered
  material, this gives a set of single cones with
  opening angle 2? around the irradiation vector.
• For white incident X-ray source and powdered
  material, energy-dispersive detector at fixed 2?
  angle sees a set of discrete energy peaks

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Aside X-ray Diffraction

• X-ray diffraction is usually done with a
  plane-wave X-ray source
• For monochromatic X-radiation and a single
  crystal, this gives a distribution of points of
  constructive interference around the sphere.
• For monochromatic X-radiation and a powdered
  material, this gives a set of single cones with
  opening angle 2? around the irradiation vector.
• For white incident X-ray source and powdered
  material, energy-dispersive detector at fixed 2?
  angle sees a set of discrete energy peaks

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Aside X-ray Diffraction

• X-ray diffraction is usually done with a
  plane-wave X-ray source
• For monochromatic X-radiation and a single
  crystal, this gives a distribution of points of
  constructive interference around the sphere.
• For monochromatic X-radiation and a powdered
  material, this gives a set of single cones with
  opening angle 2? around the irradiation vector.
• For white incident X-ray source and powdered
  material, energy-dispersive detector at fixed 2?
  angle sees a set of discrete energy peaks

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Kikuchi pattern formation
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Kikuchi pattern formation
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Kikuchi pattern formation
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Kikuchi pattern formation
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Kikuchi pattern formation
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Band detection
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Pattern indexing
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EBSD experiment modes

• Point analysis

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EBSD experiment modes

• Orientation mapping

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EBSD experiment modes

• Grain mapping

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EBSD experiment modes

• Texture

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EBSD experiment modes

• Phase discrimination (automated point counting!)