3D scanning of the Rembrandt-painting Syndics of the Drapers’ Guild. X-rays from a material x ray fluorescence pdf has been excited by bombarding with high-energy X-rays or gamma rays.
The phenomenon is widely used for elemental analysis and chemical analysis, particularly in the investigation of metals, glass, ceramics and building materials, and for research in geochemistry, forensic science, archaeology and art objects such as paintings and murals. Figure 1: Physics of X-ray fluorescence in a schematic representation. When materials are exposed to short-wavelength X-rays or to gamma rays, ionization of their component atoms may take place.
Ionization consists of the ejection of one or more electrons from the atom, and may occur if the atom is exposed to radiation with an energy greater than its ionization energy. X-rays and gamma rays can be energetic enough to expel tightly held electrons from the inner orbitals of the atom. The removal of an electron in this way makes the electronic structure of the atom unstable, and electrons in higher orbitals “fall” into the lower orbital to fill the hole left behind. In falling, energy is released in the form of a photon, the energy of which is equal to the energy difference of the two orbitals involved.
Thus, the material emits radiation, which has energy characteristic of the atoms present. Each element has electronic orbitals of characteristic energy. Following removal of an inner electron by an energetic photon provided by a primary radiation source, an electron from an outer shell drops into its place.
There are a limited number of ways in which this can happen, as shown in Figure 1. L transition is called Lα, and so on. Each of these transitions yields a fluorescent photon with a characteristic energy equal to the difference in energy of the initial and final orbital. Once sorted, the intensity of each characteristic radiation is directly related to the amount of each element in the material.