Sensitive Films for Optical Detection of Ammonia and Nitrogen Dioxide
نویسنده
چکیده
The sol-gel technology allows preparation of the thin silica lms ranging in porosity from dense to highly porous. These lms can function as matrix binding molecules of pH-sensitive indicators and can be utilized as sensitive coatings for intensity based planar evanescent wave chemical sensors. This paper is devoted to manufacturing technology and characterization of highly porous silica lms deposited on soda-lime glass substrates, impregnated with bromocresole purple and cresole red. Two di erent methods of impregnation were used: dip coating, which entails sensitization of both silica lms deposited on each side of a substrate and selective deposition of a dye solution on single side of the substrate. Manufactured sensitive lms were tested toward in uence of gaseous ammonia and nitrogen dioxide on their spectral characteristics of the absorption coe cient and the imaginary part of the refractive index. It was shown that bromocresole purple allows detection of both gases: NH3 and NO2.
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