Spectroscopic X-ray methods build on the dependence on X-ray energy. This dependence can be used to identify elements since every element has its unique absorption edges and fluorescence lines. This provides a way to detect most elements in the periodic table even inside an object and at very low concentrations. X-ray spectroscopy and fluorescence is used in many fields, such as material science, biology, forensics, environmental science and industrial applications.
The object can be characterized either by how its absorption and scattering change with respect to the energy of the incident X-ray beam or by the energies of the photons and electrons that are emitted from the object. What can be measured varies largely over the range of spectroscopic methods, as does the requirements on the equipment. When elemental contrast and spatial resolution are to be combined, the incident X–ray radiation is commonly focused into a small spot or beam at the object. This requires both an X-ray source with high brightness and X-ray optics designated for the specific task.