Photoluminescence properties of silica aerogel during sintering process

We report photoluminescence spectra measured for two series of silica aerog el sintered at 1000 degrees C in different time intervals. In the photolumi nescence spectra of nonsintered sample, bands at 1.8, 2.0 and 2.2 eV are id entified. During sintering process, the bands at 1.8 and 2.0 eV decrease an d vanish, while the band at 2.2 eV shows more complicated behavior. Accordi ng to infrared spectra of the same samples we find that the photoluminescen ce band at 1.8 eV originates from nonbridged oxygen hole center defect, and that at 2.0 eV originates from silane in the gel network. Nonstoichiometri c SiOx causes photoluminescence band at 2.2 eV.