WD-XRF instrument (Tiger Bruker S8). Principal:The basis of X-ray fluorescence spectrometry is the interaction of X-ray photons from a separate excitation source with atoms of the elements of interest found in the sample (filter deposit). When these excitation photons interact with the atoms in the sample, the photons cause the ejection of inner shell electrons. Outer shell electrons then fall into these vacancies. These transitions result in emission of Xrays characteristic of the element. The energy of the characteristic X-ray is equal to the difference in the electron binding energies of the two electron shells involved in the transition. Because the electron binding energies are a function of the atomic number, the energy of the X-ray is characteristic of the element.