Comparison of dynamics of EU3+ in different Y2O3 nanostructured materials and with sol-gel produced SiO2

Transient hole burning due to population redistribution among the hyperfine levels was studied in Y2O3 : Eu3 + nanocrystals produced both by laser eva poration and by sol-gel techniques. The hole line widths in the two samples exhibit a very different temperature dependences. It appears that while th e dynamics of the laser-produced nanocrystals is dominated by electron-phon on interactions with the size-restricted normal modes of the nanoparticles, the dynamics of the sol-gel produced nanostructured material is controlled by the some other mechanism, e.g. disorder. Persistent spectral hole burni ng and fluorescence line narrowing experiments were performed on sol-gel pr oduced SiO2 glass containing Y3 + and Eu3 +. While the spectral and tempera ture dependencies of the hole width are similar to that found in regular gl ass, the line width is some similar to 30 times larger, suggesting that in sol-gel produced glass the dynamical effects of the two-level systems are m uch stronger than in regular glass. The difference in homogeneous line widt h measured by hole burning and fluorescence line narrowing suggests the pre sence of spectral diffusion in this system. (C) 1999 Elsevier Science B.V. All rights reserved.