ELECTRON MICROSCOPY
Fayez Alghofaily
General Introduction
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Greeting
Knowing each other
New start
Rules ( Punctuality & Attendance )
Terminology
Language
Students Rights
Office for help
Course Introduction
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EM & LM
5 types of EM
Principles of Microscopy
Histology
Tissue Preparation
Microorganisms
EM and Pathology
Applications of EM
Learning objectives
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Introduction ( definition, compounds & uses)
Electronic Microscope (EM) & Light Microscope
Types of Electronic Microscope (EM)
1.
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Transmission electron microscope (TEM)
Scanning electron microscope (SEM)
Reflection electron microscope (REM)
Scanning transmission electron microscope (STEM)
Low-voltage electron microscope (LVEM)
Introduction
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An electron microscope is a type of microscope that
produces an electronically-magnified image of a
specimen for detailed observation.
Beam of electrons
Greater resolving power ; electrons have
wavelengths < photons (about 100.000 shorter)
EM magnification is 2.000.000x compared with
2000x of LM
electrostatic and electromagnetic lenses while LM
glass lenses
Uses
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Biological & inorganic specimens
 Microorganisms
 Cells
 large
molecules
 biopsy samples
 metals, and crystals
 Industrially, used for quality control
Bacteria
Bacteria
Cell
Viruses
1. Transmission Electron Microscope ) TEM)
1. Transmission Electron Microscope
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TEM is The original form of electron microscope
high voltage electron beam
tungsten filament cathode is electron source
The electrons are emitted by an electron gun
The electron beam is accelerated by an anode (40 to 400
keV)
focused by electrostatic and electromagnetic lenses
transmitted through the specimen that is in part transparent
to electrons and in part scatters them out of the beam.
When it emerges from the specimen, the electron beam
carries information about the structure of the specimen that
is magnified by the objective lens system of the microscope.
1. Transmission Electron Microscope
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The spatial variation in this information (the
"image") is viewed by projecting the magnified
electron image onto a fluorescent viewing screen
The image can be photographically recorded
Resolution of the TEM is limited primarily by
spherical aberration
The ability to determine the positions of atoms
within materials has made the HRTEM an important
tool for nano-technologies research and
development.
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