Science Atlas

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Instruments

X-ray Diffractometer

Also Known As XRD

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An X-ray diffractometer aims a beam of X-rays at a crystalline sample and measures the angles and intensities of the diffracted beams, from which the spacing of the crystal's atomic planes can be calculated using Bragg's law. Max von Laue discovered in 1912 that a crystal diffracts X-rays, work for which he received the 1914 Nobel Prize in Physics; William Henry Bragg and his son William Lawrence Bragg used the effect to build the first X-ray spectrometer in 1913 and to work out the equation, now called Bragg's law, that turns a diffraction pattern into a crystal structure, sharing the 1915 Nobel Prize in Physics for the achievement.

Facts
Open Questions
Resolution
Not stated as a numeric figure in the cited source. 2
No angstrom-level resolution figure given in this general article.
Operating Range
Not stated as a numeric figure for modern instruments; historically, X-rays of about 1 angstrom wavelength were used for this technique. 2
Source gives no modern instrument wavelength or diffraction-angle range, only a historical wavelength figure.
Invented Year
1913 1
Measures
The angles and intensities of X-rays diffracted by a crystalline sample, from which the spacing of the crystal's atomic planes is calculated. 2
Operating Principle
Governed by Bragg's law: X-rays scattered from evenly spaced atomic planes in a crystal combine constructively only at specific angles set by the plane spacing and the X-ray wavelength. 2
Cross-Tradition Connections

Invented By

William Henry Bragg, Scientists

Designed and built the first ionization X-ray spectrometer in 1912 to 13 with his son Lawrence, announced in their joint paper of April 1913; the two shared the 1915 Nobel Prize in Physics for the work.

William Lawrence Bragg, Scientists

Worked out the diffraction law behind the X-ray spectrometer his father William built in 1912 to 13; the two shared the 1915 Nobel Prize in Physics.

Used In

Sources
1. X-ray Diffraction Spectrometer (Britannica)
Encyclopaedia BritannicaView the Source
2. X-ray Diffraction (Wikipedia)
WikipediaBasics section
Quote, Basics section
X-rays scattered from adjacent planes will combine constructively when the angle...results in a path-length difference that is an integer multiple n of the X-ray wavelength
View the Source
Condensed Matter Physics (Wikipedia)
WikipediaUsed In: Solid-State PhysicsView the Source
Max von Laue (Britannica)
Encyclopaedia BritannicaUsed In: Von Laue's X-ray Diffraction ExperimentView the Source
William Lawrence Bragg (Britannica)
Encyclopaedia BritannicaUsed In: Bragg's Analysis of Sodium ChlorideView the Source
Maurice Wilkins (Britannica)
Encyclopaedia BritannicaUsed In: Wilkins's DNA X-ray Diffraction StudiesView the Source
Rosalind Franklin (Wikipedia)
WikipediaUsed In: Photograph 51View the Source
Crystallography (Wikipedia)
WikipediaUsed In: CrystallographyView the Source
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