Transmission electron microscopy

FYS4340

• FYS4340

• Theory based on ”Transmission electron microscopy” by D. B. Williams and C.B. Carter
• Part 1, 2 and standard imaging techniques (part 3)
• Practical training on the TEM

• FYS9340

• Theory same as FYS4340 + additional papers related to TEM and diffraction.
• Teaching training.
• Perform practical demonstrations on the TEM for the master students.

Electron microscopy are based on three possible set of techniqes

• Electron microscopy are based on three possible set of techniqes

The interesting objects for EM is not the average structure or homogenous materials but local structure and inhomogeneities

• The interesting objects for EM is not the average structure or homogenous materials but local structure and inhomogeneities

1839, George Airy: there should be a natural limit to the optical microscopes.

• 1839, George Airy: there should be a natural limit to the optical microscopes.

• 1872, both Ernst Abbe and Hermann von Helmholtz: Light is limited by the size of the wavelength.

1857, The cathode-ray tube was invented

• 1857, The cathode-ray tube was invented

• 1896, Olaf Kristian Birkeland experimenting with the effect of parallel magnetic fields on the electron beam of the cathode-ray tub concluded that cathode rays that are concentrated on a focal point by a magnet are as effective as parallel light rays that are concentrated by means of a lens.

1926, Hans Busch, ”Founder of the electron optics” published his theory on the trajectories of electrons in magnetic fields.

• 1926, Hans Busch, ”Founder of the electron optics” published his theory on the trajectories of electrons in magnetic fields.

• 1928, Graduate student Ruska worked on refining Busch’s work.

• The energy of the electrons in the beam was not uniform resulting in fuzzy images.
• Knoll and Ruska were able design and construct electron lenses and the first realization of an electron microscope.”

1897, J.J. Thomson

• 1897, J.J. Thomson
• Concludes that electrons have particle nature.
• 1924, Louis de Broglie
• Hypothesis: Matter on the scale of subatomic particles possesses wave characteristics. The speed of low-mass subatomic particles, such as electrons, is related to wavelength .

• 1927, Davisson and Germer and Thomson and Reid

• Both demonstrated the wave nature of electrons by independently performing electron diffraction experiments

Knoll and Ruska, first TEM in 1931

• Knoll and Ruska, first TEM in 1931

• Idea and first images published in 1932

• By 1933 they had produced a TEM

• with two magnetic lenses which gave

• 12 000 times magnification.

1939 Elmiskop by Siemens Company

• 1939 Elmiskop by Siemens Company

• 1941 microscope by Radio corporation of America (RCA)

• First instrument with stigmators to correct for astigmatism. Resolution limit below 10 Å.

Spherical aberration coefficient

• Spherical aberration coefficient

1956 independent observations of dislocations by:

• 1956 independent observations of dislocations by:

• Hirsch, Horne and Wheland and Bollmann

• -Started the use of TEM in metallurgy.

• 1956 Menter observed lattice images from materials with large lattice spacings.

• 1965 Komoda demonstrated lattice resolution of 0.18 nm.

• Until the end of the 1960’s it was mainly used to test resolution of microscopes.

• 1971/72 Cowley and Iijima

• Observation of two-dimensional lattice images of complex oxides

• 1971 Hashimoto, Kumao, Hino, Yotsumoto and Ono

• Observation of heavy single atoms, Th-atoms

Early 1970’s: Development of energy dispersive x-ray (EDX) analyzers started the field of analytical EM.

• Early 1970’s: Development of energy dispersive x-ray (EDX) analyzers started the field of analytical EM.

• Development of dedicated HREM

• Electron energy loss spectrometers and scanning transmission attachments were attached on analytical TEMs.

• Small probes making convergent beam electron diffraction (CBED) possible.

Development of combined high resolution and analytical microscopes.

• Development of combined high resolution and analytical microscopes.

• An important feature in the development was the use of increased acceleration voltage of the microscopes.

• Development of Cs corrected microscopes

• Probe and image

• Improved energy spread of electron beam

• More user friendly Cold FEG
• Monocromator

Transmission Electron microscope (TEM)

• Transmission Electron microscope (TEM)

• Electron energies usually in the range of 80 – 400 keV. High voltage microscopes (HVEM) in the range of 600 keV – 3 MeV.

• Scanning electron microscope (SEM) early 1960’s

• dedicated Scanning TEM (STEM) in 1968.

• Electron Microprobe (EMP) first realization in 1949.

• Auger Scanning Electron Microscopy (ASEM) 1925, 1967

• Scanning Tunneling Microscope (STM) developed 1979-1981

• Because electrons interact strongly with matter, elastic and inelastic scattering give rise to many different signals which can be used for analysis.

Show both particle and wave properties

• Show both particle and wave properties

• Electrons can be accelerated to provide sufficient short wave length for atomic resolution.

• Due to high acceleration voltages in the TEM relativistic effects has to be taken into account.