Fluorescence induced by radioluminescence and applications

Abstract

Two processes explain radioluminescence of organic and inorganic materials. Exposition of organic materials to ionizing particles leads to the excitation of the molecules of the matrix. The relaxation leads to photon emission. In the case of the inorganic materials a self-trapped exciton (STE) propagates in the crystal until it reaches and excites an impurity; the relaxation of this impurity may be radiative.We observed that lanthanides (ErIV or NdIV) doped materials (porous or ED2 glasses) show some characteristic emission rays. The spectra are quite similar to the expected ones for inorganic materials, while these materials are organic. We developed a model explaining how the radioluminescence of the organic materials excites the lanthanide ions, and then the observed radioluminescence emission spectra can be explained by the Judd-Ofelt theory.Several materials have been studied: erbium doped porous glass (ErIV:PG), neodymium doped ED2 glass (NdIV:ED2), and also a sample of titan sapphire (Ti:Sa) as a comparison sample for inorganic materials. These samples have been exposed to H 2 + , 4 He ++ , 12 C ++ ions accelerated up to 4.1 MeV with a Van de Graaff accelerator.The emission spectra have been measured and a study of the luminescence lifetime of the material has been made. Luminescence lifetime of the characteristic rays is dependent on the radiation dose. These observations allow us to conclude that the lanthanide ions are well excited by the standard radioluminescence of the undoped material. Also, studies have been made as a function of the deposited energy to investigate the potential applications. All these results will be presented and discuted.