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Luminescent properties and singlet oxygen production using CeF 3 :Tb 3+ -based nanoparticles modified with SiO 2 and protoporphyrin IX (PpIX) were studied. CeF 3 :Tb 3+ nanopowder was prepared via sol–gel route, with subsequent surface coating by SiO 2 layer and the conjugation with photosensitive PpIX molecules. Radioluminescence spectra suggest an energy transfer from Ce 3+ to Tb 3+ ions and from Tb 3+ to molecules of PpIX photosensitizer. The energy transfer was confirmed by photoluminescence decay curves. Singlet oxygen production was detected using a reaction of 1 O 2 with 3’-(p-aminophenyl) fluorescein (APF) chemical probe after X-Ray excitation. Qualitative changes in time resolved photoluminescence spectra in the region of 520 nm indicate 1 O 2 generation. Studied nanocomposites may be good candidates for the application in X-ray induced photodynamic therapy. [ABSTRACT FROM AUTHOR]

Using radiation method, a set of Eu doped LuAG nanopowders was prepared with Eu concentrations varying from 0.1 to 10 at.%. We studied the concentration dependence of Eu 3+ emission spectra and decays from the 5 D 0 level in the red part of the spectra. Photoluminescence measurements were complemented with radioluminescence spectra to investigate the scintillation efficiency of the samples. The results were compared with the earlier published characteristics of Eu-doped LuAG phosphors prepared by other methods. Furthermore, based on obtained results we determined an optimum europium concentration for LuAG based X-ray phosphor. [ABSTRACT FROM AUTHOR]

We study the temperature dependence of delayed recombination decay intensity in a variety of scintillating crystals based on garnet hosts in a wide temperature range 8–500 K. Previous work on several scintillating materials based on silicate hosts showed nonzero constant signal from very low temperatures up to about 120 K. This observation supported a previously suggested hypothesis on low temperature losses of fast scintillation light due to quantum tunneling between the activator and nearby traps. In garnets, the subject of the present article, we observe practically constant signal in the entire monitored temperature range. We thus further test and confirm the quantum tunneling hypothesis in a different class of scintillating materials. We also show that there is no thermal ionization of the activator’s excited state in all materials studied, well above room temperature. [ABSTRACT FROM AUTHOR]