Bragg's theorem

Bragg's theorem describes how waves, like X-rays or neutrons, reflect off the regular atomic structure inside a crystal. When the waves hit the crystal, they bounce off the atomic layers in specific directions that cause constructive interference—meaning the waves add up to make a stronger signal. This only occurs at certain angles related to the spacing between atomic layers and the wavelength of the waves. By analyzing these angles, scientists can determine the crystal’s atomic arrangement. Essentially, Bragg's theorem helps us peek inside materials to see their microscopic structure using wave reflections.