The Davisson—Germer experiment (1927) was the first measurement of the wavelengths of ► electrons. C. J. Davisson, who worked in the Bell Research Laboratories, received the Nobel Prize in Physics for the year 1937 together with George P. Thomson from the University of Aberdeen in Scotland, who independently also found experimental indications of electron diffraction. According to the Copenhagen Interpretation of Quantum Mechanics, ► wave-particle duality leads to particles also exhibiting wave-like properties like extension in space and interference.
Clinton J. Davisson (1881–1958) and Lester H. Germer (1896–1971) investigated the reflection of electron beams on the surface of nickel crystals. When the beam strikes the crystal, the nickel atoms in the crystal scatter the electrons in all directions. Their detector measured the intensity of the scattered electrons with respect to the incident electron beam. Their normal polycrystalline samples exhibited a very smooth angular distribution of scattered electrons. In early 1925, one of their samples was inadvertently recrystallized in a laboratory accident that changed its structure into nearly monocrystalline form. As a result, the angular distribution manifested sharp peaks at certain angles. As Davisson and Germer soon found out, other monocrystalline samples also exhibited such anomalous patterns, which differ with chemical constitution, angle of incidence and orientation of the sample. Only in late 1926 did they understand what was going on, when Davisson attended the meeting of the British Association for the Advancement of Science in Oxford. There Born spoke about de Broglie's ► matter-waves and Schrodinger's ► wave mechanics. Their later measurements completely confirmed the quantum mechanical predictions for electron wavelength λ as a function of momentum p: λ = h/p. But their initial experiments (unlike G.P Thomson's) were conducted in the context of industrial materials research on filaments for vacuum tubes, not under any specific theoretical guidance.
KeywordsScattered Electron Nickel Atom Antecedent Condition Atomic Particle Initial Kinetic Energy
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- 2.A. P. French, E. F. Taylor: An Introduction to Quantum Physics (Stanley Thornes Publishers, Cheltenham 1998, 64–72, Chapman & Hall 1979)Google Scholar
- 3.K. Krane: Modern Physics (Wiley, New York 1983, 89–93)Google Scholar
- 4.A. Russo: Fundamental research at Bell laboratories: The discovery of electron diffraction. Historical Studies in the Physical Sciences 12, 117–160 (1981)Google Scholar
- 5.P. A. Tipler: Modern Physics (Worth Publishers, New York 1978, 169–73)Google Scholar