Q:
What is Scanning & Transmission Electron Microscopy?



A:
  • Major installations are standard equipment
    in large corporations and universities, costing ~ $1 million.

  • TEM is principally a research instrument with Angstrom
    level resolution in best cases (similar to AFMs).

  • Sample preparation is a significant problem. Nonconductive
    samples require a conductive coating (gold or carbon sputtered).

  • SEM/EDAX is more versatile and can be used for
    failure analysis.

  • SEM Main Advantage: Combination of excellent topographical
    information at 5,000 to 20,000x for most industrial uses,
    coupled with elemental analysis of features. Research instruments
    go to 500,000x and higher.

  • SEM Main Disadvantages: Cost and sample preparation time.
    mounted on cantilever arm 100 to 200 microns long. Tip radii
    are in the nano meter range.

  • Exception to expensive SEM installations:
    "The Personal SEM" by RJ Lee Instruments, Ltd, Trafford, PA
    Cost range - $65,000 to $85,000, depending on options selected.

  • Can analyze individual particles from components.
    Note: composition data are semi-quantitative without standards,
    and lower limits to elements detected, usually around sodium,
    without the more expensive unit and Light Element attachment.