In EM measurements, after a core electron has been emitted from an ionized atom, this atom quickly decays from its excited state to its ground state and thus may produce a characteristic X-ray (“radiative”) or an Auger electron (“nonradiative”). Therefore, these processes of inner-shell ionization loss are different aspects of the same phenomenon. Both processes compete for the decay.
As shown in Figure 4965, when the excited atom has electrons ejected from its inner core states, the subsequent filling of the core hole is accompanied by either Auger electron, X-ray fluorescence, or light emission. X-ray fluorescence dominates
over Auger processes for deeper core relaxation.
Figure 4965. Schematic illustration of inner-shell ionization when sufficiently energetic electron induces ejection of a tightly bound inner-shell atomic electron, leaving the atom in an excited state and thus resulting in the emission of characteristic X-ray or Auger electron.