Davisson-Germer experiment
The Davisson-Germer experiment[1] is considered an unequivocal demonstration of the wave nature of matter and a fundamental demonstration of the viability of the theory of quantum mechanics.
In 1927, Clinton Joseph Davisson (1881-1958) and Lester Halbert Germer (1896-1971) tested de Broglie’s hypothesis[2] of the wave behaviour of matter by beaming electrons at varying levels of energy at a crystal lattice of nickel. Since the sample of nickel was composed of layers or planes of crystals at regular intervals, the expectation was that the electrons would be scattered at varying angles from the crystal layers. Subsequently, the electrons scattering from the different planes would then interfere with each other.
Davisson and Germer then measured the current (energy) and angle of the scattered electrons. Their data showed clear evidence of interference patterns typical of waves and those patterns were correlated with the different planes of the crystals.
References
- ↑ Published by Davisson and Germer (1927) in Nature, V119, pp. 558-560. Reflection of electrons by a crystal of nickel.
- ↑ Louis-Victor-Pierre-Raymond de Broglie (1892-1987) published this theory in his doctoral thesis, Recherches sur la théorie des quanta (Researches on the quantum theory), Thesis, Paris, in 1924. de Broglie posited that matter would act as a wave and that wavelength was related to its momentum as is true of a photon. The wavelength, lambda, a function of Planck’s constant and momentum (λ=h/p where h is Planck’s constant and p is momentum) is actually inversely proportional to momentum and thus larger objects have diminishing wavelengths, explaining why macroscopic objects do not have an apparent wave behaviour—the greater the momentum the smaller the wavelength.
- ↑ Davisson Germer Experiment Dept of Physics and Astronomy, University of New Mexico. Retrieved April 20th, 2008
- ↑ Davisson-Germer Experiment Carl. R. Nave (2006) Dept of Physics and Astronomy, Georgia State University
- ↑ Wave nature of electron Carl. R. Nave (2006) Dept of Physics and Astronomy, Georgia State University
- ↑ C. J. Davisson Discovery of Electron Waves-Nobel Lecture 1937 Nobel Foundation
- ↑ Quantum Theory 1 Sayffie Maleki (2006) Dept of Physics, Union College
- ↑ Planck, Einstein, and de Broglie David J. Raymond (2006) New Mexico Tech
- ↑ Nature of Mass Calphysics Institute