Bragg Diffraction

Bragg's law: 2d·sin(θ) = nλ. X-rays scattered by crystal planes interfere constructively when path difference equals an integer multiple of wavelength.

2d·sin(θ) = nλ

d-spacing (Å) 2.50 Wavelength λ (Å) 1.54 Diffraction order n 1 Angle θ (°) 18.0

Bragg condition: –
2d·sin(θ) = – Å
nλ = – Å
Intensity: –

W.L. Bragg (1913, age 22!): derived reflection law for crystal planes. Shared Nobel Prize with father W.H. Bragg (1915). Used to determine protein structures (Watson-Crick DNA, 1953 used Franklin's X-ray data).