J. Phys. IV France 129 (2005) 131-136
An optical detection NH3 gas by means of a-WO3 thin films based on SPR technique*E. Maciak, Z. Opilski, T. Pustelny and M. Bednorz
Department of Optoelectronics Institute of Physics, Silesian University of Technology, 2 Krzywoustego St., 44-100 Gliwice, Poland
An optical sensor for ammonia gas, based on the surface plasmon resonance (SPR) method has been investigated. The surface plasmon resonance (SPR) is very sensitive, and so the optical technique used in chemical sensing. The angle of incident of light at which a resonant effect is observed, as well as the dip of a resonant are very sensitive to variations of the optical parameters of the medium on the surface active-plasmon metal layer. The sensing structure was made as follows. The gold layers were coated by means of vacuum evaporation on a substrate, 1 mm thick, made of BK7 glass slide. The thickness of Au was about 48 nm. An active layer of WO3 was deposited by thermal evaporation on the gold film. The sensor structure was coupled on immersion oil with a prism coupler. A change of the intensity of light of the plasmon dip was observed when chemical active films (WO3) were exposed to varying concentrations of NH3. Optical ammonia gas sensors display a very fast response time and a fast regeneration time at room temperature.
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