A Quantum Cascade Laser-Based Optical Sensor for Continuous Monitoring of Environmental Methane in Dunkirk (France)

• Published in: Sensors 2016-02, Vol.16 (2), p.224-224
• Main Authors: Maamary, Rabih, Cui, Xiaojuan, Fertein, Eric, Augustin, Patrick, Fourmentin, Marc, Dewaele, Dorothée, Cazier, Fabrice, Guinet, Laurence, Chen, Weidong
• Format: Article
• Language: English
• Subjects: Absorption; Air - analysis; Analytical chemistry; campaign measurement; Chemical Sciences; Continuous radiation; Environmental Engineering; environmental methane; Environmental Monitoring; Environmental Sciences; France; Humans; Laser applications; Lasers, Semiconductor; Meteorological parameters; Methane; Methane - isolation & purification; Methane - toxicity; Optical measurement; Optical measuring instruments; QCL-based sensor; Quantum cascade lasers; Sensors
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s16020224

A room-temperature continuous-wave (CW) quantum cascade laser (QCL)-based methane (CH4) sensor operating in the mid-infrared near 8 μm was developed for continuous measurement of CH4 concentrations in ambient air. The well-isolated absorption line (7F2,4 ← 8F1,2) of the ν4 fundamental band of CH4 located at 1255.0004 cm(-1) was used for optical measurement of CH4 concentration by direct absorption in a White-type multipass cell with an effective path-length of 175 m. A 1σ (SNR = 1) detection limit of 33.3 ppb in 218 s was achieved with a measurement precision of 1.13%. The developed sensor was deployed in a campaign of measurements of time series CH4 concentration on a site near a suburban traffic road in Dunkirk (France) from 9th to 22nd January 2013. An episode of high CH4 concentration of up to ~3 ppm has been observed and analyzed with the help of meteorological parameters combined with back trajectory calculation using the Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model of NOAA.