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Proceedings Paper

Laser photoacoustic sensor for air toxicity measurements
Author(s): Coorg R. Prasad; Jie Lei; Wenhui Shi; Guangkun Li; Ilya Dunayevskiy; C. Kumar N. Patel
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Paper Abstract

US EPA's Clean Air Act lists 187 hazardous air pollutants (HAP) or airborne toxics that are considered especially harmful to health, and hence the measurement of their concentration is of great importance. Numerous sensor systems have been reported for measuring these toxic gases and vapors. However, most of these sensors are specific to a single gas or able to measure only a few of them. Thus a sensor capable of measuring many of the toxic gases simultaneously is desirable. Laser photoacoustic spectroscopy (LPAS) sensors have the potential for true broadband measurement when used in conjunction with one or more widely tunable laser sources. An LPAS gas analyzer equipped with a continuous wave, room temperature IR Quantum Cascade Laser tunable over the wavelength range of 9.4 μm to 9.7 μm was used for continuous real-time measurements of multiple gases/chemical components. An external cavity grating tuner was used to generate several (75) narrow line output wavelengths to conduct photoacoustic absorption measurements of gas mixtures. We have measured various HAPs such as Benzene, Formaldehyde, and Acetaldehyde in the presence of atmospheric interferents water vapor, and carbon dioxide. Using the preliminary spectral pattern recognition algorithm, we have shown our ability to measure all these chemical compounds simultaneously in under 3 minutes. Sensitivity levels of a few part-per-billion (ppb) were achieved with several of the measured compounds with the preliminary laboratory system.

Paper Details

Date Published: 9 May 2012
PDF: 12 pages
Proc. SPIE 8366, Advanced Environmental, Chemical, and Biological Sensing Technologies IX, 836608 (9 May 2012); doi: 10.1117/12.919241
Show Author Affiliations
Coorg R. Prasad, Science & Engineering Services, Inc. (United States)
Jie Lei, Science & Engineering Services, Inc. (United States)
Wenhui Shi, MassTech Inc. (United States)
Guangkun Li, MassTech Inc. (United States)
Ilya Dunayevskiy, Pranalytica, Inc. (United States)
C. Kumar N. Patel, Pranalytica, Inc. (United States)

Published in SPIE Proceedings Vol. 8366:
Advanced Environmental, Chemical, and Biological Sensing Technologies IX
Tuan Vo-Dinh; Robert A. Lieberman; Günter Gauglitz, Editor(s)

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