Practice question

Diffraction arises from long-range three-dimensional order where atoms are positioned with periodic repetition defined by unit cell parameters a, b, c and angles. Constructive interference occurs only when scattering from thousands of identical cells aligns in phase according to Bragg's law. This periodic array amplifies weak atomic scattering into measurable spots. Properties like polarizability govern Raman scattering, optical density affects absorption, heat capacity relates to energy storage, but none produce coherent diffraction. Consequently, ability to form crystals with consistent unit cell repetition enables determination of otherwise invisible atomic arrangements in biological macromolecules.