%0 Journal Article
%K aerogel
%K air pressure
%K oxygen concentration
%K oxygen molecules
%K photoluminescence
%A Michael R Ayers
%A Arlon J Hunt
%B Journal of Non-Crystalline Solids
%D 1998
%G eng
%P 343-347
%R 10.1016/S0022-3093(98)00051-9
%T Molecular oxygen sensors based on photoluminescent silica aerogels
%V 225
%8 04/1998
%X <p>Photoluminescent silica aerogel acts as the active element of an optical sensor for molecular oxygen. The luminescent aerogel is prepared by the action of energized reducing gases on a standard silica aerogel. Intensity of aerogel photoluminescence decreases as the collision frequency between oxygen molecules and the luminescent carriers in the aerogel matrix increases. This behavior is a characteristic of many photoluminescent materials and arises from a transfer of energy from the aerogel to surrounding oxygen molecules. A sensor for oxygen concentration or air pressure can therefore be simply constructed utilizing an ultraviolet source for excitation and a suitable detector for the emitted visible signal. Stern-Volmer quenching constants for the aerogel sensing element are 1.55×10<sup>-2</sup> Torr<sup>-1</sup> for hydrophilic aerogel and 2.4×10<sup>-3</sup> Torr<sup>-1</sup> for hydrophobic aerogel.</p>