Q.Describe briefly how an electron-diffraction experiment of the Davisson-Germer type provided direct experimental confirmation of de Broglie's hypothesis of matter waves.

The Davisson-Germer experiment, carried out by Clinton Davisson and Lester Germer in 1927, was the first direct experimental confirmation of de Broglie's matter-wave hypothesis. Their apparatus heated a filament with a low-tension battery to emit electrons by thermionic emission, accelerated these electrons through a known potential difference using a high-tension battery, collimated them into a narrow beam using two thin aluminium diaphragms, and directed this beam onto a single crystal of nickel. Because a crystal's regularly spaced atomic planes can act as a natural three-dimensional diffraction grating for any wave whose wavelength is comparable to that spacing -- and an electron's de Broglie wavelength, at typical laboratory accelerating voltages, is indeed of that same order ($10^{-10}$ m) -- any genuine wave character in the electron beam should show up as a diffraction pattern in how the beam scatters off the crystal. …