Читать книгу Quantum Physics is NOT Weird - Paul J. van Leeuwen - Страница 34

The discovery of the wave behavior of electrons in 1931 resulted – within 4 years after Davisson's publication in Nature – in the construction of the first electron microscope by Ernst Ruska ^[26] (1906-1988), together with the German electrical engineer Max Knoll (1897-1969) .

When using a normal light microscope, the size of the tiniest details that are distinguishable is limited by the wavelength of visible light. Details smaller than the wavelengths of this light cannot be distinguished. The light waves do not reflect but just bend around these small objects like waves bend around a buoy at sea. Moving to the use of shorter wavelengths – UV light – is not a viable option since glass does not transmit UV light very well. But, when you are using electrons, you can control their wavelength through their energy. When you give them enough energy to make their wavelength small enough, you can render much smaller details ‘visible’. The prepared microscopic specimen must be able to withstand the electron bombardment as well as the vacuum needed for the electrons to move unhindered. Focusing, as with glass lenses for visible light, can be done for electrons beams with magnetic coils because of the electron charge. See figure 4.14.

Figure 4.14: Electron Microscope.

Source: Wikimedia Commons. Author: Graham Beards

The electron microscope is the first technical instrumental application of quantum physics.