The invention is disputed. Max Knoll and Ernst Ruska built the first working transmission electron microscope at the Technische Hochschule in Charlottenburg in 1931. Reinhold Rüdenberg filed U.S. patents in 1932 at Siemens-Schuckert and is recognized as the inventor under patent law, though it is unclear whether he had a working instrument when the patents were filed. The 1986 Nobel Prize was awarded for the invention, but both Knoll (died 1969) and Rüdenberg (died 1961) were ineligible to receive a share of it.
What resolution does an electron microscope achieve compared to a light microscope?
Electron microscopes achieve a resolution of about 0.1 nanometers, compared to roughly 200 nanometers for optical light microscopes. This is possible because the wavelength of an electron can be more than 100,000 times smaller than the wavelength of visible light. High-resolution transmission electron microscopes with aberration correctors can resolve detail to below 0.5 angstroms (50 picometres).
What is the difference between a TEM and a SEM?
A transmission electron microscope (TEM) fires a high-voltage electron beam through a thin specimen, using electrons with energies typically in the range 20-400 keV, to produce structural images. A scanning electron microscope (SEM) rasters a lower-energy beam, generally below 20 keV, across the surface of a specimen and detects the secondary electrons, backscattered electrons, or other signals that result from that interaction, producing detailed surface images.
When was the first commercial electron microscope produced?
Siemens produced the first commercial electron microscope in 1938, a year after the company financed the work of Ernst Ruska and Bodo von Borries and employed Helmut Ruska to develop biological applications for the instrument. Siemens followed with a commercial transmission electron microscope in 1939.
What is aberration correction in electron microscopy and when was it introduced?
Aberration correction uses electro-optical components combined with computer-controlled lens alignment to reduce the optical flaws, primarily spherical aberration, that historically limited electron microscope resolution. Harald Rose and Maximilian Haider demonstrated the first working correction in TEM mode in 1998 using a hexapole corrector. Ondrej Krivanek and Niklas Dellby achieved correction in STEM mode in 1999 using a quadrupole/octupole corrector.
Why are electron microscope samples usually prepared and placed in a vacuum?
Air molecules would scatter the electron beam, degrading the image, so samples must be held in vacuum. Biological and hydrated specimens also require stabilization, ultrathin sectioning, and staining to survive in the beam and to provide sufficient electron optical contrast. Cryogenic fixation, vitrifying specimens by rapid freezing, has been used since the 1980s as an alternative preparation method that reduces preparation artifacts.