Excitation mechanism of europium ions embedded into TiO2 nanocrystalline matrix

In this work, the excitation mechanism of Eu3+ ions embedded into nanocrystalline TiO2 film obtained by Low Pressure Hot Target Reactive Sputtering has been investigated by means of photoluminescence, photoluminescence excitation, transmission and surface photovoltage spectroscopy. The strong emission related to europium ions in the visible range has been observed at a non resonant excitation wavelength suggesting an efficient excitation transfer from the matrix to the ions. Based on obtained results, indirect excitation mechanism of europium ions has been confirmed and discussed. Moreover, surface activity strongly depending on environment conditions, has been also observed. (C) 2009 Elsevier B.V. All rights reserved.