X-ray spectrometer

X-rays, one of the most exciting discoveries of the late 19th century, had been shown to react strangely when exposed to crystals, producing patterns of spots on a photographic plate. However, what these observations of X-ray diffraction meant was largely unexplained.

In 1912 physicists William Bragg (1862-1942) and his son Lawrence Bragg (1890-1971) worked out a formula that linked the X-ray diffraction pattern with a crystal’s atomic structure. In a series of experiments at the University of Leeds the next year, they used their new X-ray spectrometer to produce molecular analyses of materials including diamond and rock salt.

Their discovery, known as X-ray crystallography, is still the most accurate technique to determine the structure of materials at the atomic level. For this, Bragg and his son won the Nobel Prize in Physics in 1915.

Understanding the properties of crystals, from common salt and diamonds to complex organic compounds and proteins, has allowed innumerable advances in chemistry, physics, materials science, biology and medicine.