Bragg's law

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Loi de Bragg (Fr). Bragg Gesetz (Ge). Ley de Bragg (Sp). Legge di Bragg (It)

Definition

Bragg's law provides the condition for a plane wave to be diffracted by a family of lattice planes:

2 dhkl sin θ = n λ.

where dhkl is the lattice spacing, θ the angle between the wavevector of the incident plane wave and the reflecting planes, λ its wave length and n is an integer, the order of the reflection. It is equivalent to the diffraction condition in reciprocal space and to the Laue equations.


History

Bragg (1890-1971) presented his derivation of the reflection condition at a meeting of the Cambridge Philosophical Society on 11 November 1912. His paper was published in 1913 (Bragg W.L., 1913, The Diffraction of Short Electromagnetic Waves by a Crystal, Proc. Cambridge Phil. Soc., 17, 43-57. For details, see P. P. Ewald, 1962, IUCr, 50 Years of X-ray Diffraction, Section 5, page 64.

See also

Laue equations