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Aspects of the Application of Cavity Enhanced Spectroscopy to Nitrogen Oxides Detection
Institute of Optoelectronics, Military University of Technology, 2 Gen. S. Kaliskiego St., Warsaw 00-908, Poland
* Author to whom correspondence should be addressed.
Received: 10 April 2013; in revised form: 2 May 2013 / Accepted: 27 May 2013 / Published: 10 June 2013
Abstract: This article presents design issues of high-sensitive laser absorption spectroscopy systems for nitrogen oxides (NOx) detection. Examples of our systems and their investigation results are also described. The constructed systems use one of the most sensitive methods, cavity enhanced absorption spectroscopy (CEAS). They operate at different wavelength ranges using a blue—violet laser diode (410 nm) as well as quantum cascade lasers (5.27 µm and 4.53 µm). Each of them is configured as a one or two channel measurement device using, e.g., time division multiplexing and averaging. During the testing procedure, the main performance features such as detection limits and measurements uncertainties have been determined. The obtained results are 1 ppb NO2, 75 ppb NO and 45 ppb N2O. For all systems, the uncertainty of concentration measurements does not exceed a value of 13%. Some experiments with explosives are also discussed. A setup equipped with a concentrator of explosives vapours was used. The detection method is based either on the reaction of the sensors to the nitrogen oxides directly emitted by the explosives or on the reaction to the nitrogen oxides produced during thermal decomposition of explosive vapours. For TNT, PETN, RDX and HMX a detection limit better than 1 ng has been achieved.
Keywords: CEAS; CRDS; absorption spectroscopy; laser spectroscopy; nitrogen oxides detection; NOx detection; explosives detection
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Wojtas, J.; Mikolajczyk, J.; Bielecki, Z. Aspects of the Application of Cavity Enhanced Spectroscopy to Nitrogen Oxides Detection. Sensors 2013, 13, 7570-7598.
Wojtas J, Mikolajczyk J, Bielecki Z. Aspects of the Application of Cavity Enhanced Spectroscopy to Nitrogen Oxides Detection. Sensors. 2013; 13(6):7570-7598.
Wojtas, Jacek; Mikolajczyk, Janusz; Bielecki, Zbigniew. 2013. "Aspects of the Application of Cavity Enhanced Spectroscopy to Nitrogen Oxides Detection." Sensors 13, no. 6: 7570-7598.