Davisson

It does not provide mueh historieal perspeetive on the development of quantum meehanies. Subjeets sueh as the photoeleetrie effeet, blaek-body radiation, the dual nature of eleetrons and photons, and the Davisson and Germer experiments are not even diseussed. 

The underlying principle of RHEED is that particles of matter have a wave character. This idea was postulated by de Broglie in (1924). He argued that since photons behave as particles, then particles should exhibit wavelike behavior as well. He predicted that a particle s wavelength is Planck s constant h divided by its momentum. The postulate was confirmed by Davisson and Germer s experiments in 1928, which demonstrated the diffraction of low-energy electrons from Ni. ... 

When Davisson and Germer reported in 1927 that the elastic scattering of low-energy electrons from well ordered surfaces leads to diffraction spots similar to those observed in X-ray diffraction [2.238-2.240], this was the first experimental proof of the wave nature of electrons. A few years before, in 1923, De Broglie had postulated that electrons have a wavelength, given in A, of ... 

C. J. Davisson (New York) and G. P. Thomson (London) experimental discovery of the diffraction of electrons by crystals. 

FIGURE 1.21 Davisson and Germer showed that electrons produce a diffraction pattern when reflected from a crystal G. P. Thomson, working in Aberdeen, Scotland, showed that they also produce a diffraction pattern when they pass through a very thin gold foil. The latter is shown here. G. P. Thomson was the son of J. J. Thomson, who identified the electron (Section B). Both received Nobel prizes 1.1. for showing that the electron is a particle and G. P. for showing that it is a wave. 

The wavelike character of electrons was confirmed by showing that they could be diffracted. The experiment was first performed in 1925 by two American scientists, Clinton Davisson and Lester Germer, who directed a beam of fast electrons at a single crystal of nickel. The regular array of atoms in the crystal, with centers separated by 250 pm, acts as a grid that diffracts waves and a diffraction pattern was observed (Lig. 1.21). Since then, some molecules have been shown to undergo... 

The details of this description would be changed slightly, but not essentially, by the introduction of the spinning electron into the theory, f The experiments of Davisson and Kunsman, Phys. Rev., vol. 22, p. 242 (1923), on... 

De Broglie received the Nobel Prize in physics in 1929, only two years after experiments confirmed his theory. Davisson, a student of Nobel laureate Robert Millikan, and Thomson, the son and student of J. J. Thomson (who won the Nobel prize for discovering the electron), shared the Nobel Prize in physics in 1937. 

There was no experimental evidence for the wave nature of matter until 1927, when evidence was provided by two independent experiments. Davisson found that a diffraction pattern was obtained if electrons were scattered from a nickel surface, and Thomson found that when a beam of electrons is passed through a thin gold foil, the diffraction pattern obtained is very similar to that produced by a beam of X-rays when it passes through a metal foil. 

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