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Proceedings Paper

Air quality monitoring based on Fourier transform infrared spectroscopy
Author(s): Wei Zheng; Yan Wang; Rui Wang
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Paper Abstract

The use of optical techniques to identify and quantify atmospheric pollutants has been focused within the past two decades. Fourier Transform Infrared (FTIR) spectroscopy has proven to be a powerful tool for multi-component analysis of air quality monitoring. The technique has been used for gaseous samples by extractive sampling as well as in the open-path configuration. The present contribution has described the application of FTIR to analyze gaseous pollutants in ambient air in detail. The study for the detection limits of the interested gas, the design of the multipass White mirror system, and the experimental results are described. The White cell is employed to increase the absorbance relative to noise in the absorbance spectrum by increasing the path length without proportional loss of signal. A classical least squares (CLS) fit is used to match the scaled standards or previously measured absorption profiles to those of the observed spectrum in the specified spectral analysis regions for simultaneous quantification of the compounds of interest, plus several other ambient air constituents. The regions were chosen carefully to provide optimum detection of the compounds of interest with minimum interference by other compounds. Specially, spectrum subtraction and differential absorption concepts are introduced into FTIR data analysis. The optimal window for CO, S02, NO2, NO and CO2 would be the region at 2250-2020 cm-1, 1230-1070 cm-1, 2940-2840 cm-1, 1965-1775 cm-1, and around 668.24 cm-1 respectively. Deviations from traditional measured results for all approaches are in 10%.

Paper Details

Date Published: 27 October 2006
PDF: 6 pages
Proc. SPIE 6047, Fourth International Conference on Photonics and Imaging in Biology and Medicine, 60472H (27 October 2006); doi: 10.1117/12.710983
Show Author Affiliations
Wei Zheng, Tianjin Univ. (China)
Yan Wang, Tianjin Univ. (China)
Rui Wang, Tianjin Univ. (China)

Published in SPIE Proceedings Vol. 6047:
Fourth International Conference on Photonics and Imaging in Biology and Medicine
Kexin Xu; Qingming Luo; Da Xing; Alexander V. Priezzhev; Valery V. Tuchin, Editor(s)

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