TEM Winterworkshop 2011: electron diffraction

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Tutorial on how to index diffraction patterns, determine extinction symbols from SAED and point groups from CBED. Lesson taught at the EMAT Winterworkshop on TEM. 21 januari 2011

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  • Indexing of SAED patterns: to get information about the structure needed for studying defects needed for HREM imaging
  • toon in EMAP!
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • off course can be skipped if you know them
  • it is possible in other zones, the condition is not a Bravais condition
  • it is possible in other zones, the condition is not a Bravais condition
  • it is possible in other zones, the condition is not a Bravais condition
  • it is possible in other zones, the condition is not a Bravais condition
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • use notepad to explainMany ways, for example, use what you know = 020.both left and right same distance, so 333 or 511 with or without minus signs (-) and cyclic permutation (cp)difference between both has to be 020333 not possible: other one 313 or 353 (-, cp)511 possible: right 5-11, left 511; but also 5-1-1 and 51-1 are possiblehow to choose?use graphyc representation of reciprocal space
  • use notepad to explainMany ways, for example, use what you know = 020.both left and right same distance, so 333 or 511 with or without minus signs (-) and cyclic permutation (cp)difference between both has to be 020333 not possible: other one 313 or 353 (-, cp)511 possible: right 5-11, left 511; but also 5-1-1 and 51-1 are possiblehow to choose?use graphyc representation of reciprocal space
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • two difficulties: choose between 333 and 511, then assign the minus signs
  • 4mm
  • 4mm
  • to overcome dynamical effects.So the measured intensities can be just for ab initio structure determination and for refinement of the structure.
  • Beam precessed on a cone.Descan to keep the central beam stationary.Ewald sphere intersects the plane along an arcLess reflections excited simultaneouslyless dynamical effectsIntegrated pattern pseudo-kinematicalSymmetry improved in for example microdiffraction patterns so intensities can be used.ANIMATION : EMAP: SnO2
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