Takuma Yahaba

Photoluminescence and radiation response properties of Ce3+-doped CsCaCl3 crystalline scintillator

In this paper, we report on the photoluminescence and scintillation properties of a newly developed CsCaCl3:Ce (0.5 mol%) crystalline scintillator grown by the vertical Bridgman method. The fluorescence quantum efficiency for the Ce3+ characteristic emission bands centered at around 350–400 nm was 76% under excitation at 330 nm light. The photoluminescence decay time of the Ce3+ was approximately 32 ns. When x-ray excited the crystal, intense emission bands were observed at 350–400 nm, and could be attributed to the Ce3+ emission. The scintillation light yield of the developed crystal was ~7600 ph MeV−1 compared to a NaI:Tl commercial scintillator, and the principal scintillation decay time was approximately 340 ns plus two fast components of around 1.6 ns and 45 ns.

Fabrication and optical characterization of CdSe nanoparticles liganded with π-conjugated organic molecules of Rhodamine dyes

The resonant state between Frenkel excitons in the organic molecules and Wannier excitons in the inorganic semiconductor are predicted to lead to a new type of exciton which exhibits unique optical properties. To achieve the resonance states, strong interaction of excited states between the organic molecules and the inorganic semiconductor is necessary. In this study, we synthesized inorganic nanocrystals liganded with π-conjugated organic ligands (CdSe–Rhodamine). The emission wavelengths of the CdSe nanocrystals are tuned to those of the Rhodamine molecules. In the CdSe nanocrystals–Rhodamine B complex, the significant change was observed in the PL decay behavior. The relative intensity of the fast decay component was significantly enhanced with the addition of Rhodamine B to the CdSe solution while the decay–time constant of the fast decay time component became very close to that of Rhodamine B. The results strongly suggest that the radiative rate was significantly enhanced in the hybrid system.