3.1 Excitation sources

The ionization of the atoms can be performed using different types of sources. X-ray tube emission photons and highly energized electrons were the first types of radiation used in the early studies on x-ray properties and interactions with matter. The technology in the production of radioisotopes opened the possibility of avoiding the use of electronic devices and to obtain relatively cheap and compact sources for excitation.

With the development of particle accelerators the use of charged particles opened a multiplicity of choices for particle induced x-ray emission. The synchrotron light, featuring advantageous properties for x-ray spectroscopy, is nowadays the more advantageous, although not always economically affordable, excitation source.