Fast scintillation processes in CsCl crystals comprising semiconductor nanocrystals

We analyzed the scintillation mechanism in CsCl single crystals comprising CsPbCl₃-like semiconductor nanocrystals. A decay component with a subnanosecond lifetime was observed and ascribed to the exciton luminescence in the nanocrystals. This is the first observation of scintillation from semiconductor nanocrystals. In addition, slower components were observed and ascribed to the intraionic transition at isolated Pb²⁺ ions and the Auger-free luminescence in the CsCl matrix. Furthermore, it was shown that the nanocrystals absorbed and re-emitted the scintillation photons from the isolated Pb²⁺ ions. The results in this report clearly indicates that the semiconductor nanocrystals function as ultrafast "luminescent centers," and complicated scintillation dynamics are observed due to the luminescence from different components in the crystal and the radiative energy transfer between them.