Site distribution and thermalization effects in Europium-doped silica glasses

For the no-phonon transition 5D0->7F0 of Eu3+ in glasses, obtained by sol-gel route, emission and absorption at low temperature are not resonant. This effect is interpreted by a redistribution of the excitation energy among the different environment for the Eu3+ ion. A simple model is used to interpret the temperature evolution of the emission spectra. A good agreement is obtained with experimental results. The experimental emission spectra are simulated using the Boltzmann law and the experimental excitation spectra. The mechanism of redistribution is a phonon-assisted energy transfer process. This is confirmed by temperature dependence of decays and time resolved emission measurements.