Electron Microscopy
Introduction to Electron Microscopy
Prof. David Muller, dm24@cornell.edu Rm 274 Clark Hall, 255-4065
Ernst Ruska and Max Knoll built the first electron microscope in 1931
(Nobel Prize to Ruska in 1986)
T4 Bacteriophage
Electron Microscopy bridges the 1 nm – 1 μm gap David Muller 2008 between x-ray diffraction and optical microscopy
Tools of the Trade
AFM
MFM
Scanned Probe Microscope (includes Atomic Force Microscope)
Transmission Electron Microscope
Scanning Electron Microscope
David Muller 2008
Biological and Electronic Component Dimensions
Biological
1
Electronic Components
Logic Board Computer chip Optical Microscope
Tool
10-2
SEM
Size (m)
10-4
Mammalian cell
10-6
Bacterial cell Virus Transistor AFM/STM Gate Oxide Atom
TEM
10-8
Gene Protein
10-10 David Muller 2008
Comparison of Optical and Electron Microscopes
• Electron microscopes are operated in vacuum because the mean free path of electrons is air is short – this mean biological samples should not degas – they can either be dehydrated or frozen – pathology, not in-vivo. •Electron microscopes have higher resolution than optical microscopes – atomic resolution is possible. •Chemical imaging and spectroscopy – mapping π and σ bonds at 1nm resolution can be done. •Radiation damage is severe and limits the image quality and resolution (not as bad as x-rays or neutrons though! – see R. Henderson, Quarterly Reviews of Biophysics 28 (1995) 171-193.)
David Muller 2008
Comparison of Optical and Electron Microscopes
Light Microscope source 1st condenser 2nd condenser
TEM
SEM or STEM
Viewing screen Or CCD
specimen Objective lens Projector lenses
CA condenser aperture OA objective aperture SA selected area aperture
Image formed by scanning a small spot
David Muller 2008
Viewing screen Or CCD
Inside a Transmission Electron Microscope
High tension cable (100-200 kV) Filament Accelerating stack Double
Prof. David Muller, dm24@cornell.edu Rm 274 Clark Hall, 255-4065
Ernst Ruska and Max Knoll built the first electron microscope in 1931
(Nobel Prize to Ruska in 1986)
T4 Bacteriophage
Electron Microscopy bridges the 1 nm – 1 μm gap David Muller 2008 between x-ray diffraction and optical microscopy
Tools of the Trade
AFM
MFM
Scanned Probe Microscope (includes Atomic Force Microscope)
Transmission Electron Microscope
Scanning Electron Microscope
David Muller 2008
Biological and Electronic Component Dimensions
Biological
1
Electronic Components
Logic Board Computer chip Optical Microscope
Tool
10-2
SEM
Size (m)
10-4
Mammalian cell
10-6
Bacterial cell Virus Transistor AFM/STM Gate Oxide Atom
TEM
10-8
Gene Protein
10-10 David Muller 2008
Comparison of Optical and Electron Microscopes
• Electron microscopes are operated in vacuum because the mean free path of electrons is air is short – this mean biological samples should not degas – they can either be dehydrated or frozen – pathology, not in-vivo. •Electron microscopes have higher resolution than optical microscopes – atomic resolution is possible. •Chemical imaging and spectroscopy – mapping π and σ bonds at 1nm resolution can be done. •Radiation damage is severe and limits the image quality and resolution (not as bad as x-rays or neutrons though! – see R. Henderson, Quarterly Reviews of Biophysics 28 (1995) 171-193.)
David Muller 2008
Comparison of Optical and Electron Microscopes
Light Microscope source 1st condenser 2nd condenser
TEM
SEM or STEM
Viewing screen Or CCD
specimen Objective lens Projector lenses
CA condenser aperture OA objective aperture SA selected area aperture
Image formed by scanning a small spot
David Muller 2008
Viewing screen Or CCD
Inside a Transmission Electron Microscope
High tension cable (100-200 kV) Filament Accelerating stack Double