Braggsches

Braggsches Gesetz, commonly known in English as Bragg's law, is a fundamental relation in X-ray crystallography that describes the condition for constructive interference of X-rays scattered by crystal planes. It was formulated by William Henry Bragg and his son William Lawrence Bragg in 1913, providing a practical framework for analyzing crystal structures.

The law states that, for monochromatic X-rays of wavelength λ incident on crystal planes with spacing d, constructive interference occurs when nλ = 2d sin θ, where θ is the angle between the incident rays and the crystal planes, and n is an integer representing the order of diffraction. The diffracted beam emerges at an angle 2θ to the incident beam.

Bragg's law underpins X-ray diffraction experiments and is used to determine lattice spacings and crystal structures. By measuring diffraction angles and intensities, researchers can infer the arrangement of atoms in a material, ranging from minerals to complex biomolecules, making Bragg's law central to X-ray crystallography and structural chemistry.

Historical context: William Henry Bragg and William Lawrence Bragg were awarded the Nobel Prize in Physics in 1915 for their analyses of crystal structures by means of X-rays, establishing a practical method for crystal structure determination.

Limitations and scope: The law applies to crystals with well-defined planes and requires monochromatic X-ray radiation. It is not applicable to amorphous materials without long-range order and is typically observed for specific lattice spacings and diffraction orders.