de Broglie Wavelength

Louis de Broglie (1924): every moving particle of momentum p has an associated wave of wavelength λ = h/p.

For a particle of mass m and speed v (non-relativistic): λ = h/(mv).

For an electron accelerated through V volts: λ = h/√(2meV) = 12.27/√(V[volts]) Å.

Larger momentum (heavier or faster) ⇒ smaller wavelength.

Matter waves were experimentally verified by Davisson-Germer (electron diffraction off Ni crystal, 1927) and G.P. Thomson (electron diffraction through thin foils).

Atom-interference experiments now confirm de Broglie waves for atoms and even C₆₀ buckyballs.

de Broglie's hypothesis led directly to Schrödinger's wave equation and modern quantum mechanics.