Luminescence excitation mechanisms of rare earth doped phosphors in the VUV range

Progress in the development of new luminescent materials is directly relate d to our understanding of physical processes of energy absorption and relax ation in solids. As far as the VUV energy is concerned, the most suitable m aterials are probably the large band gap inorganic lattices activated by ra re earth ions. Optical excitation in these systems result either in a direc t excitation of the luminescence center or an excitation of the host lattic e which partly transfer the energy to the emitting levels of the activator. Every steps of the luminescence mechanism enter in competition with nonrad iative losses or undesired luminescence which have to be minimized in order to get a high luminescence efficiency. Determination of the dominant trans fer and energy loss mechanisms can be performed by time resolved luminescen ce spectroscopy using UV-VUV synchrotron radiation (SR) excitation. We repo rt here, the result of studies of a large number of rare earth doped materi als, performed in the frame of programmes for search of new efficient VUV p hosphors and scintillators. The experiments were performed using XUV-VUV SR from SuperAco and DCI storage rings at LURE. (C) 1999 Published by Elsevie r Science B.V. All rights reserved.