Transmission Electron Microscopy (TEM)

            In TEM a thin solid specimen (£ 200 nm thick) is bombarded in vacuum with a highly-focused, monoenergetic beam of electrons. The beam is of sufficient energy to propagate through the specimen. A series of electromagnetic lenses and then magnifies this transmitted electron signal. Diffracted electrons are observed in the form of a diffraction pattern beneath the specimen. This information is used to determine the atomic structure of the material in the sample.  

Range of Elements: TEM does not specifically identify elements measured

Destructive: Yes, during specimen preparation

Chemical Bonding Information: Sometimes, indirectly from diffraction and image simulation

Quantification: Yes, atomic structures by diffraction; defect characterization by systematic image analysis

Accuracy: Lattice parameters to four significant figures using convergent beam diffraction

Detection limits: One monolayer for relatively high-Z materials

Depth Resolution: None, except there are techniques that measure sample thickness

Lateral Resolution: Better than 0.2 nm on some instruments

Imaging/mapping: Yes

Sample Requirements: Solid conductors and coated insulators. Typically 3-mm diameter, < 200-nm thick in the center

Main Uses: Atomic structure and microstructural analysis of solid materials, providing high lateral resolution

Instrument Cost: $300,000-$1,500,000

Size: 100ft² to a major lab

 

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