In physics, a Bragg plane is a plane in reciprocal space, at right angles. The Bragg plane is defined as part of the Von Laue condition for diffraction peaks in x-ray diffraction crystallography.

Considering the adjacent diagram, the arriving x-ray plane wave is defined by:

is the incident wave vector given by:

is the wavelength of the incident photon. While the Bragg formulation assumes a unique choice of direct lattice planes and specular reflection of the incident X-rays, the Von Laue formula only assumes monochromatic light and that each scattering center acts as a source of secondary wavelets as described by the Huygens principle. Each scattered wave contributes to a new plane wave given by:

direction is that the path difference between the photons is an integer multiple (m) of their wavelength. We know then that for constructive interference we have:

:

Now consider that a crystal is an array of scattering centres, each at a point in the Bravais lattice which are Bravais lattice vectors, the condition then becomes:

An equivalent statement (see mathematical description of the reciprocal lattice) is to say that:

. This reciprocal space plane is the Bragg plane.

See also

• X-ray crystallography

• Reciprocal lattice

• Bravais lattice

• Powder diffraction

• Kikuchi line

• Brillouin zone

References