X-ray spectroscopy is a technique that detects and measures photons, or particles of light, that have wavelengths in the X-ray portion of the electromagnetic spectrum. It’s used to help scientists understand the chemical and elemental properties of an object.

There are several different X-ray spectroscopy methods that are used in many disciplines of science and technology, including archaeology, astronomy and engineering. These methods can be used independently or together to create a more complete picture of the material or object being analyzed.

History

Wilhelm Conrad Röntgen, a German physicist, was awarded the first Nobel Prize in physics in 1901 for his discovery of X-rays in 1895. His new technology was quickly put to use by other scientists and physicians, according to the SLAC National Accelerator Laboratory.

Charles Barkla, a British physicist, conducted research between 1906 and 1908 that led to his discovery that X-rays could be characteristic of individual substances. His work also earned him a Nobel Prize in physics, but not until in 1917.

The use of X-ray spectroscopy actually began a bit earlier, in 1912, starting with a father-and-son team of British physicists, William Henry Bragg and William Lawrence Bragg. They used spectroscopy to study how X-ray radiation interacted with atoms within crystals. Their technique, called X-ray crystallography, was made the standard in the field by the following year and they won the Nobel Prize in physics in 1915.

How X-ray spectroscopy works

When an atom is unstable or is bombarded with high-energy particles, its electrons transition from one energy level to another. As the electrons adjust, the element absorbs and releases high-energy X-ray photons in a way that’s characteristic of atoms that make up that particular chemical element. X-ray spectroscopy measures those changes in energy, which allows scientists to identify elements and understand how the atoms within various materials interact.

There are two main X-ray spectroscopy techniques: wavelength-dispersive X-ray spectroscopy (WDXS) and energy-dispersive X-ray spectroscopy (EDXS). WDXS measures the X-rays of a single wavelength that are diffracted by a crystal. EDXS measures the X-ray radiation emitted by electrons stimulated by a high-energy source of charged particles.