2. Outline
• light microscope vs Electron microscope
• Types of Electron microscope
• Transmission electron micrscope
• Tem imaging
• Tem applications
• Advanateges
• Disadvantages
3. • Light
microscope
- simple to use
- Poor surface view
- Uses light rays to
illuminate specimens
Source
- Lenses are made of
glass
- Low magnification of
up to 1,500x
- Resolving power :-
200nm
• Electron microscope
- users require technical skills
- Good surface view and
internal detailnesses
- Uses a beam of electrons to
view specimens
- Lenses are made of
electromagnetic
- High magnification of up to
1,000,000x
- Resolving power :- .2 nm
- operates under a high
vacuum
4. Types of Electron microscope
• Scanning electron
microscope (SEM)
• Transmission electron
microscope(TEM )
5. TRANSMISSION ELECTRON
MICROSCOPE ( TEM )
• TEMs consist of the following components:
• An electron source
• Thermionic Gun
• Electron beam
• Electromagnetic lenses
• Vacuum chamber
• 2 Condensers
• Sample stage
• Phosphor or fluorescent screen
• Computer
6. TEM imaging
• A Transmission Electron Microscope produces a high-resolution,
black and white image from the interaction that takes place
between prepared samples and energetic electrons in the vacuum
chamber.
• During transmission, the speed of electrons directly correlates to
electron wavelength; the faster electrons move, the shorter
wavelength and the greater the quality and detail of the image.
7. TEM applications
• TEMs provide topographical, morphological,
compositional and crystalline information.
• This information is useful in the study of
crystals and metals, but also has industrial
applications
• TEMs can be used in semiconductor analysis
and production and the manufacturing of
computer and silicon chips.
8. Advantages
• TEMs have a wide-range of applications and can be utilized
in a variety of different scientific, educational and industrial
fields
• TEMs provide information on element and compound
structure
• Images are high-quality and detailed
• TEMs are able to yield information of surface features,
shape, size and structure
• They are easy to operate with proper training
9. Disadvantages
• TEMs are large and very expensive
• Laborious sample preparation
• Potential artifacts from sample preparation
• Operation and analysis requires special
training
• TEMs require special housing and
maintenance
• Images are black and white
