• Canadian Centre for Electron Microscopy
  • +1 905 525 9140 (Ext. 20400)

Glossary and Links

There are a lot of acronyms in electron microscopy. Here we give a very basic idea of the techniques associated with some commonly used terms. The links at the bottom of the page may also be useful for finding more information.

HRTEM

High-Resolution Transmission Electron Microscopy

This technique provides images of the internal structure and features of a material or a device. With conventional TEM magnification up to about 650k times is possible; with high-resolution TEM (HRTEM) atomic resolution can be achieved.

These images show dislocation structure, grain structure, precipitates; depending on the grain/precipitate size one can obtain lattice structure information and orientation relationships.

HRTEM investigations require more microscope time then conventional TEM imaging; more demanding sample preparation is required.

A wide range of materials can be imaged; best are metals and ceramics, amorphous or crystalline; bio-materials and polymers can also be imaged although both imaging and sample preparation can be more demanding.

SEM – EDXS

Scanning Electron Microscopy – Energy Dispersive X-ray Spectroscopy

The electron beam is scanned across the polished surface of an SEM sample; the detected x-ray signal gives elemental information. The sample composition can be mapped and the composition can be quantified if data from appropriate standards is available. A wide range of elements can be detected, generally Z = 5 and higher atomic numbers.

STEM – EDXS

Scanning Transmission Electron Microscopy – Energy Dispersive X-ray Spectroscopy

The electron beam is scanned across the thin-slice TEM sample; the detected x-ray signal gives elemental information. The sample composition can be mapped and the composition can be quantified if data from appropriate standards is available. A wide range of elements can be detected, generally Z = 5 and higher atomic numbers. The technique is not as sensitive as EELS.

STEM – EELS

Scanning Transmission Electron Microscopy – Electron Energy Loss Spectroscopy

The electron beam is scanned across the sample; the detected electron energy signal gives elemental information. High magnification, atomic resolution is possible with the correct sample geometry (a thin slice). The sample composition can be mapped and the composition can be quantified if data from appropriate standards are available. A wide range of elements can be detected; generally boron and higher atomic numbers if in non-trace amounts. The technique can also can give information on bonding and valence; e.g. for identification of specific oxides.

STEM – HAADF

Scanning TEM (STEM) high angle annular dark field (HAADF) imaging provides images with contrast from different elements, most often at very high magnification giving atomic resolution. This shows the material’s structure as well as giving details of defects and boundaries.

STEM imaging combined with an analytical technique (EDXS or EELS) to identify and quantify composition gives a full picture of material of interest.

TEM Imaging

This technique provides images of the internal structure and features of a material or a device. With conventional TEM magnification up to about 650k times is possible; with high-resolution TEM (HRTEM) atomic resolution can be achieved.

These images show dislocation structure, grain structure, precipitates; depending on the grain/precipitate size one can obtain lattice structure information and orientation relationships.

Conventional TEM is relatively quick, sample preparation is less demanding. It is an excellent technique when features of interest are on the order of 100 nm or larger; it is also ideal for initial investigation or sample overview.

A wide range of materials can be imaged; best are metals and ceramics, amorphous or crystalline; bio-materials and polymers can also be imaged although both imaging and sample preparation can be more demanding.

Tomography

A technique where many 2D images of an object are obtained and then built up to create a 3D virtual model of the object. The 2D images can be serial slices or images taken at different angles as the object is rotated about one axis. Multiple imaging techniques can be used to make the 2D images. FIB – SEM is often used for serial sectioning; TEM imaging is used with rotating samples. Alignment of the images and data reconstruction are required to create a useful 3D model from the data.

Top