Basics of electron microscopy

1. ELECTON MICROSCOPY
THE BASICS

2. FIRST TRANSMISSION ELECTRON MICROSCOPE
1931- RUSTA AND KNOLL

3. ELECTRON MICROSCOPE
 IS A VACCUUM
 ELECTRONS BEHAVE LIKE LIGHT
 ELECTRON HAS A NEGATIVE CHARGE THEREFORE ELECTRIC AND MAGNETIC FIELDS AFFECT
ELECTRONS

4. ELECTRON GUN
 FILAMENT: HEAT UP
 CYLINDER: FOCUSES ELECTRONS
 ANODE: ACCELERATED ELECTRONS

5. ELECTRON COLUMN
 VACUUM SYSTEM
 ELECTRON AND MAGNETIC LENSES
 APPERTURES
 SPECIMEN
 IMAGE RECORDING

6. ELECTRON-SPECIMEN
 ABSORPTION: SAME MATERIAL AND THICKNESS
 ELECTRON SCATTERING: CREATE CONTRAST
 REFLECTION (ELECTRON SCATTERING): REFLECTION OF MAIN ELECTRON BEAM – BACKSCATTERED
ELECTRONS
 EMISSION (INELASTIC SCATTERING): MAIN BEAM ELECTRONS TRANSFER ENERGY TO ORBITTING
ELECRONS RESULTING IN EMISSION OF SECONDARY ELECTRONS. THIS LEADS TO PRODUCTION
OF X-RAYS AND PHOTONS
 DIFFRACTION: THIS TAKES PLACE IN CRYSTALLINE SAMPLES BECAUSE THEY CAUSE ELECTRON
SCATTERING TO VARIOUS DIRECTIONS

7. PREPARING BIOLOGICAL SPECIMENS
 FIXATION MAY BE REQUIRED TO PRESERVE THE STRUCTURE OF SPECIMEN
 IT IS NOT NEEDED IN SMALL SAMPLES
 FIXATION CAN BE CHEMICAL OR CRYO

8. SCANNING ELECTRON MICTOSCOPY
ELECTRON GUN
ANODE
MAGNETIC LENS
SCANNING COILS
BACKSCATTERED
ELECTRON DETECTOR
SPECIMEN
SECONDARY
ELECTRON DETECTOR
SCANNER