Bragg’s Law is the fundamental principle that explains how X-rays are diffracted by crystals. Simply put, it states that X-rays will produce a strong diffraction signal only when the X-rays “bounce” off parallel atomic planes in the crystal in a way that the scattered waves reinforce each other.
- This happens only at specific angles, which depend on the spacing between the atomic planes and the wavelength of the X-rays.
- When this condition is met, the scattered X-rays interfere constructively, producing a detectable diffraction peak.
Why it’s important in XRD:
- It allows us to relate the diffraction angles to the distances between atomic planes in the crystal.
- Using Bragg’s Law, XRD can be used to identify crystal structures, determine lattice parameters, and measure interatomic spacings.
- It is the core principle behind interpreting XRD patterns, whether for phase identification or detailed structural analysis.
In short, Bragg’s Law explains why X-rays produce a pattern when they hit a crystal and lets us extract atomic-level information from that pattern.