Multi-gas sensing based on photoacoustic spectroscopy using tunable laser diodes
Multi-hydrogenated compounds detection based on photoacoustic (PA) spectroscopy is reported. Three near-infrared semiconductor lasers are used with a resonant PA cell operated in its first longitudinal mode to monitor methane, water vapour and hydrogen chloride in the parts per million range. The design of our cell results from simulations performed in order to optimise its performances. Influence of the buffer gas on the PA signal has also been analysed, both theoretically and experimentally. A reduction of the PA signal of almost one order of magnitude has been observed between N2 and He, which demonstrates the importance of the buffer gas in PA spectroscopy. Finally, detection limits of 0.5 ppm of CH4 and 3 ppm of HCl has been achieved experimentally in nitrogen and an H2O sensitivity of 0.2 ppm has been estimated. © 2004 Elsevier B.V. All rights reserved.
Keywords: Semiconductor lasers ; Distributed feedback lasers ; Chemical sensors ; Frequency modulation ; Absorption ; Light sources ; Photoacoustic spectroscopy ; Optical fibers ; Gas detectors ; Mathematical models
Lab. of Nanophotonics and Metrology, Swiss Fed. Institute of Technology, CH-1015 Lausanne, Switzerland Compilation and indexing terms, Copyright 2008 Elsevier Inc. 04518721524 1386-1425 Wavelength modulation spectroscopy (WMS) Frequency modulation spectroscopy (FMS) Multi-gas sensing Trace gas monitoring
Record created on 2008-09-29, modified on 2016-12-05