Optical and photoluminecsence properties of powdered silica aerogel ar-SiOx

Optical and photoluminescent properties of powdered silica aerogel ar-SiOx have been investigated using FTIR spectroscopy and photoluminescence lifetime spectroscopy. Powdered silicagel was prepared from sodium silicate water solution using sol-gel technique. FTIR spectra revealed the presence of numerical hydroxyl groups such as bonded Si - OH and non-bonded -OH groups which determines oxidative properties of the material and confirmed that investigated material consists of two phases: stoichiometric SiO₂ and non-stoichiometric SiO_x. The intense photoemission was detected in blue-green region with stipulated peaks at 1.9, 2.0, 2.2 and 2.6 eV. It was shown that emission properties of powdered silica aerogel ar-SiO_x caused by the presence of numerical oxygen defect centres. Optical sensor response of powdered silica aerogel under treatment of liquid adsorbate (ethyl alcohol water solutions) have been revealed. The reversible PL quenching has been observed in the wide range of ethyl concentration. Maximum sensor response of ar-SiO_x samples was estimated to be S_m1=1.2 for 96% ethyl alcohol solution and S_m2=2.1 for pure water.