Ultraviolet photoluminescence of porous silica

Excitation pattern and decay kinetics of ultraviolet photoluminescence of porous 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 recently observed ultraviolet emission of oxidized porous Si and Si nanostructures. Emission intensity is found to be controlled by the material specific surface. 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 sensibly different than in glassy SiO2, suggesting a revision of previous assignments of ultraviolet emissions in oxidized porous Si and Si nanostructures. (C) 2000 American Institute of Physics. [S0003-6951(00)01122-0].