Internally Referenced Ammonia Sensor Based on an Electrochemically Prepared Porous SiO2 Photonic Crystal


  • This material is based upon work supported by the National Science Foundation under Grant # DMR-0452579. Supporting Information is available online from Wiley InterScience or from the author.


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An oxidized porous silicon photonic crystal possessing two reflectance peaks is infused with bromothymol blue, yielding a pH-responsive ammonia vapor sensor. One reflectance peak overlaps the absorbance band of the deprotonated dye while the other appears in a “clear” spectral region. Simultaneous monitoring of both reflectance peaks corrects for large changes in probe light intensity.