Davisson-Germer Experiment The Davisson-Germer experiment demonstrated the wave nature of the electron, confirming the earlier hypothesis of deBroglie. Putting wave-particle duality on a firm experimental footing, it represented a major step forward in the development of quantum mechanics. The Bragg law for diffraction had been applied to x-ray diffraction, but this was the first application to particle waves.

Davisson and Germer designed and built a vacuum apparatus for the purpose of measuring the energies of electrons scattered from a metal surface. Electrons from a heated filament were accelerated by a voltage and allowed to strike the surface of nickel metal.

Davisson, C. J., "Are Electrons Waves?," Franklin Institute Journal 205, 597 (1928)

The electron beam was directed at the nickel target, which could be rotated to observe angular dependence of the scattered electrons. Their electron detector (called a Faraday box) was mounted on an arc so that it could be rotated to observe electrons at different angles. It was a great surprise to them to find that at certain angles there was a peak in the intensity of the scattered electron beam. This peak indicated wave behavior for the electrons, and could be interpreted by the Bragg law to give values for the lattice spacing in the nickel crystal. The experimental data above, reproduced above Davisson's article, shows repeated peaks of scattered electron intensity with increasing accelerating voltage. This data was collected at a fixed scattering angle. Using the Bragg law, the deBroglie wavelength expression, and the kinetic energy of the accelerated electrons gives the relationship

In the historical data, an accelerating voltage of 54 volts gave a definite peak at a scattering angle of 50°. The angle theta in the Bragg law corresponding to that scattering angle is 65°, and for that angle the calculated lattice spacing is 0.092 nm.

For that lattice spacing and scattering angle, the relationship for wavelength

as a f of voltage is empirically

`

end

^ R. Eisberg, R. Resnick（1985）．“Chapter 3 – de Broglie's Postulate—Wavelike Properties of Particles”，Quantum Physics: of Atoms, Molecules, Solids, Nuclei, and Particles，2nd Edition，John Wiley & Sons．ISBN 0-471-87373-X．

C. Davisson, L. H. Germer（1970年）． “Reflection of electrons by a crystal of nickel”．Nature．Vol. 119：558–560．

对我们来说是画符.

为德布罗意获诺奖铺平道路，顺便Davisson自己也拿到个。贝尔实验室早年最出名的实验之一，可惜现在朗讯要裁掉基础研究部门，这些事情以后就很难再有咯。

分享一道例题，用那个角度是算不出来的，于是老师就让我们用一个自己觉得对的值。看了帖子，我决定用50度试试。