Narrow line spectra induced by Er3+ in silica glasses containing SnO2 nanocrystals

Silica glasses containing SnO2 nanocrystals and Er3+ ions were prepared by the sol-gel route and proper annealing treatments. A few samples were prepared with fluorinated Si precursors. Er3+ transitions from the ground 4I15/2 to the 4I13/2, 4I11/2, 4I 9/2, 4F9/2, 4S3/2, 2H11/2, and 4F7/2 excited manifolds were monitored by means of high resolution (as fine as 0.1 cm-1) Fourier Transform spectroscopy in the wave number (6000-22000 cm-1) and temperature (9-300 K) range, respectively. Broad absorption spectra were observed in silica samples simply doped with Er3+, as expected for Er3+ in a glassy environment. In samples containing also SnO 2 nanocrystals, complex, narrow line Er3+ related spectra were monitored. The lines become sharper and sharper by lowering the temperature to 9 K, as expected for Er3+ ions embedded in an ordered (crystalline) environment. The nature and origin of different surroundings probed by the Er3+ line spectra are discussed.