Ultraviolet photoluminescence of porous silica

Excitation pattern and decay kinetics of ultraviolet photoluminescence of p orous silica are investigated between 4.5 and 10 eV by means of synchrotron radiation. Spectra are dominated by a 3.7 eV emission similar to the recen tly observed ultraviolet emission of oxidized porous Si and Si nanostructur es. Emission intensity is found to be controlled by the material specific s urface. Other emissions are observed at 2.9, 3.8, and 4.2 eV. All emissions show lifetimes of a few nanoseconds. Spectral and kinetic features are sen sibly different than in glassy SiO2, suggesting a revision of previous assi gnments of ultraviolet emissions in oxidized porous Si and Si nanostructure s. (C) 2000 American Institute of Physics. [S0003-6951(00)01122-0].