TEM

Transmission Electron Microscopy (TEM) THAMBI JORGE IVAN CIFUENTES ENRIQUE LOPEZ

Seminary Content

 Fundamentals of TEM

 Parts of the TEM

(Lopez)

(Thambi)

 Techniques (Lopez)  Applications of TEM

(Ivan)

What is TEM?  Microscopy technique  Beam of electrons  Ultra thin specimen

 Image magnified

FUNDAMENTALS  Resolution

 Higher resolution than light microscopes  Small wave length of electrons comparing with

photons

History  Erns Abbe: wavelength of the light.  Plucker 1858: deflection of electrons, magnetic fields.  Ferdinand Braun: creation of CRO’s

 Hans Busch: lens maker’s equation, applicable to electrons.

History…  De Broglie 1927: wavelenghts of electrons.

 Max Knoll, Ernst Ruska, Borries 1928: design of the first TEM.

 Albert Premus, James Hillier 1938: first TEM in North America.

Techniques  Diffraction contrast: variation in intensity of electron diffraction across

the specimen.  Objective aperture allows the diffraction contrast.  Recombination effect of the diffracted and transmitted intensity

suppresses the diffraction contrast.  Diffraction contrast important to see features.

Bright Field Imaging

Dark Field Imaging

Example of DF / BF imaging

Convergent Beam Electron Diffraction  Incident beam focused with condenser and objective lens.  Incident rays come at different angles.  Diffracted beams in set of divergent cones.  The cones form disks, patterns.  Patterns, point group symmetry of the crystal structure.

Conventional illumination / CB illumination

Convergent beam image

High Resolution Imaging

HRTEM