Other Free Encyclopedias » Online Encyclopedia » Encyclopedia - Featured Articles » Contributed Topics from A-E

Davisson, Clinton Joseph

electron electrons tube western

(1881–1958) US physicist: discovered experimentally the diffraction of electrons by crystals.

After graduating from the University of Chicago and taking his PhD at Princeton, Davisson worked at the Carnegie Institute of Technology (1911–17). He then joined the Bell Telephone Laboratory (then the Western Electric Co Laboratory) for wartime employment after being refused enlistment in 1917, and subsequently stayed until his retirement in 1945.

The Davisson and experiment, which confirmed hypothesis that particles could behave like waves (and thus fundamentally altered modern physics), was initially accidental and in part due to a patent suit. Western Electric were protecting their patent for three-element vacuum tube (with an oxide-coated filament) against similar tube with a tungsten filament developed by him at General Electric Co. In order to help settle the suit (which dragged on for a decade), Davisson and Germer measured electron emission from oxide-coated platinum under ion bombardment. The purpose was to establish that the electron emission did not depend upon positive ion bombardment due to oxygen traces in the tube, and therefore that Langmuir’s tube did not fundamentally differ from that already under patent. This they did, and the Supreme Court eventually ruled in Western Electric’s favour. In the meantime Davisson and C H Kunsman investigated electron emission under electron bombardment as an easy extension to the work, and found a small number of primary electrons with the full energy of the incident beam deflected back alongside the many low energy secondary electrons. In 1925 an accidental explosion of a liquid-air bottle heavily oxidized a nickel surface which Davisson was investigating, and after heating to clean it (which also recrystallized it from polycrystalline into a few large crystals) it displayed a maximum scattering at a particular angle.

On visiting Oxford in 1926 and hearing of Broglie’s recent work, postulating wave behaviour for an electron, Davisson realized that he had seen diffraction maxima in the electron wave pattern. In 1927 Davisson, with Germer, obtained conclusive evidence that electron beams were diffracted on reflection by nickel crystals and had the wavelength predicted by Broglie. For this he shared the 1937 Nobel prize for physics with , who had observed similar electron diffraction with high-energy electrons passing through metal foil.

Davy, Sir Humphry [next] [back] Davis, Sammy, Jr. (1925–1990)

User Comments

Your email address will be altered so spam harvesting bots can't read it easily.
Hide my email completely instead?

Cancel or