X-ray fluorescence characteristic is the emission of secondary ( or fluorescent ) X-rays from a material that has been excited with high-energy radiation. The phenomenon is utilized in X-ray fluorescence analysis for determining the elemental composition of metals, glasses, ceramics, and other materials.
Substituting materials by the irradiation of short-wavelength X-rays, the components are ionized by the discharge of one or more electrons. Is the energy of the radiation is high enough, in addition to the bonding electrons and the electrons from the inner shells are knocked out. This is the electronic structure of the atom unstable, and electrons of higher shells are covered by emission of a characteristic of the element radiation in the resulting gap.
Electronic transitions in a calcium atom.
Typical energy-dispersive X-ray fluorescence spectrum