Abstract
We report on a fiber-coupled, quartz-enhanced photoacoustic spectroscopy (QEPAS) near-IR sensor for sequential detection of methane (CH4 or C1) and ethane (C2H6 or C2) in air. With the aim of developing a lightweight, compact, low-power-consumption sensor suitable for unmanned aerial vehicles (UAVs)-empowered environmental monitoring, an all-fiber configuration was designed and realized. Two laser diodes emitting at 1653.7 nm and 1684 nm for CH4 and C2H6 detection, respectively, were fiber-combined and fiber-coupled to the collimator port of the acoustic detection module. No cross talk between methane and ethane QEPAS signal was observed, and the related peak signals were well resolved. The QEPAS sensor was calibrated using gas samples generated from certified concentrations of 1% CH4 in N2 and 1% C2H6 in N2. At a lock-in integration time of 100 ms, minimum detection limits of 0.76 ppm and 34 ppm for methane and ethane were achieved, respectively. The relaxation rate of CH4 in standard air has been investigated considering the effects of H2O, N2 and O2 molecules. No influence on the CH4 QEPAS signal is expected when the water vapor concentration level present in air varies in the range 0.6–3%.
Highlights
Leakages from oil and gas pipelines and wildland fires significantly contribute to the greenhouse effect and degrade the air quality
To empower real-time environmental monitoring based on unmanned vehicles exploration, we report in this work a novel, lightweight, low-power-consumption, fiber-based quartz-enhanced photoacoustic spectroscopy (QEPAS) sensor devoted to methane and ethane detection in the near-IR spectral range
The methane QEPAS signals displayed identified as the valuesby maximizing signals.methane–99.9% nitrogen mixture through the sensor in Figure 2b were acquired flushingC1 a 0.1%
Summary
Leakages from oil and gas pipelines and wildland fires significantly contribute to the greenhouse effect and degrade the air quality. The methane QEPAS signals displayed identified as the valuesby maximizing signals.methane–99.9% nitrogen mixture through the sensor in Figure 2b were acquired flushingC1 a 0.1%
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