Sub-ppm multi-gas photoacoustic sensor.
A photoacoustic multi-gas sensor using tuneable laser diodes in the near-infrared region is reported. An optimized resonant configuration based on an acoustic longitudinal mode is described. Automatic tracking of the acoustic resonance frequency using a piezo-electric transducer and a servo electronics is demonstrated. Water vapour, methane and hydrogen chloride have been measured at sub-ppm level in different buffer gas mixtures. The importance of the system calibration in presence of several diluting gases is discussed. Finally, trace gas measurements have been assessed and detection limits (signal-to-noise ratio=3) of 80 ppb at 1651.0 nm for CH(4), 24 ppb at 1368.6 nm for H(2)O and 30 ppb at 1737.9 for HCl have been demonstrated.
Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratory of Nanophotonics and Metrology (NAM), CH-1015 Lausanne, Switzerland. Jean-Phillipe.Bensson@epfl.ch
Jean-Philippe
JP
Besson
Stéphane
S
Schilt
Luc
L
Thévenaz
D002623:Chemistry Techniques, Analytical / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005740:Gases / Q000032:analysis*; D006851:Hydrochloric Acid / Q000032:analysis*; D007834:Lasers; D008697:Methane / Q000032:analysis*; D013053:Spectrophotometry / Q000295:instrumentation*; D014867:Water / Q000032:analysis*
D005740:Gases; D014867:Water; D008697:Methane; D006851:Hydrochloric Acid