Figure 4.

Fourier transform infrared transmission spectra in the attenuated total reflection configuration. Partially oxidised porous silicon (top), free SO nanoparticles (magenta), aerogels containing nanoparticles of SO (green) and LH (blue) types, and pure silica aerogels (bottom). The spectra are all baseline corrected and normalised to 3% transmission at the Si-O-Si absorption band at approximately 1,100 cm⁻¹ so as to show the relative strength of the Si-H modes indicated by the vertical dashed lines. The peaks indicated by arrows in the aerogel spectra are due to CH₃ absorptions.