30 July 1999 Amplified detection of chemicals using photoluminescence and interferometry from a porous silicon chip: detection of nitrobenzene and 2,4-dinitrotoluene in air
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Abstract
The detection of nitroaromatic molecules by porous silicon films has been explored using direct and indirect detection methods. In the direct method, detection is achieved by monitoring the photoluminescence of a nanocrystalline porous Si films upon exposure to the analyte of interest. Photoluminescence is quenched upon adsorption of the nitroaromatic, presumably via an electron transfer mechanism. For nitrobenzene a detection limit of 350 ppm (after an exposure time of < 2 minutes) was observed. For 2,4-dinitrotoluene, a much lower detection limit of 250 ppb (after an exposure time of < 6 minutes) was obtained. Both the detection limit and the response time of the material can be lowered by the use of a catalyst (PtO2 at 250 degree(s)C) in the carrier gas line upstream of the porous silicon detector. The enhanced sensitivity comes from catalytic oxidation of the nitroaromatic to NO2, which irreversibly oxidizes the surface of the porous Si, providing an integrating function. The demonstrated limit for NO2 detection is 70 ppb. A complementary detection technique involving measurement of spectral shifts of a porous Si film Fabry-Perot interferometer upon oxidation will also be presented.
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Michael J. Sailor, Michael J. Sailor, William C. Trogler, William C. Trogler, Stephane Content, Stephane Content, Sonia Letant, Sonia Letant, Honglae Sohn, Honglae Sohn, Yeshaiahu Fainman, Yeshaiahu Fainman, Paul E. Shames, Paul E. Shames, } "Amplified detection of chemicals using photoluminescence and interferometry from a porous silicon chip: detection of nitrobenzene and 2,4-dinitrotoluene in air", Proc. SPIE 3713, Unattended Ground Sensor Technologies and Applications, (30 July 1999); doi: 10.1117/12.357144; https://doi.org/10.1117/12.357144
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