ABSTRACT
Luminescence excited by an electron beam is called cathodoluminescence and luminescence excited by energetic particles, that is, α-ray, ß-ray or a neutron beam, or by γ-ray, is called either radioluminescence or scintillation. In solids, both the electron beam and the high-energy radiation induce ionization processes, which in turn generate highly energetic electrons. The reflected electrons can be classified into three types: elastically scattered primary electrons, inelastically scattered primary electrons, and secondary electrons. The secondary electrons mentioned here are those electrons generated by the primary electrons in the solid and are energetic enough to overcome the work function of the solid surface. The luminescence excited by energetic particles is radioluminescence. The excitation mechanism of radioluminescence has its own characteristic processes, though it involves ionization processes similar to the cathodoluminescence processes. In inorganic compounds having complex ions and organic compounds, the excitation energy is transferred to the luminescence centers through the molecular energy levels.
