Studies of some optical materials, like fluored glass, crystals or polymers, show an important luminescence in the visible spectrum, near UV, due to high energy radiation (α, β, n, X-rays or γ). This phenomenon, known as radioluminescence or scintillation, is especially used for medical physics and dosimetry. Those materials can be doped by heavy metal ions, like rare-earth elements. Recent studies show that the irradiation of such rare-earth doped scintillators, can emit visible spectral rays. Those are corresponding to rare-earth transitions, in addition to the normal radioluminescence of the undoped material. Those peaks cannot correspond to the propagation of the self-trapped exciton in the inorganic scintillator. We actually believe the rare-earth ions are just excited by the light (blue) emitted by the scintillator, and that finally this phenomenon is not electronic but photonic, thus a kind of radioluminofluorescence.
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