QEPAS Sensor for Simultaneous Measurements of H₂O, CH₄, and C₂H₂ Using Different QTFs

Abstract

A multi-gas quartz enhanced photoacoustic spectroscopy (QEPAS) sensor based on three quartz tuning forks (QTFs) with different response frequencies for trace gas detection was proposed and experimentally demonstrated. Three near-infrared DFB lasers are used to monitor water vapor, methane, and acetylene in the parts per million range. The sensor system was first evaluated for individual H2O, CH4, and C2H2 detection, respectively. Subsequently, the sensor system was evaluated for simultaneous H2O, CH4, and C2H2 detection. Finally, trace gas measurements have been assessed and minimum detection limit (MDL) of 1.3 ppmv at 1368.597 nm for H2O, 79 ppmv at 1653.722 nm for CH4, and 5 ppmv at 1532.83 nm for C2H2 have been demonstrated. The continuous monitoring of H2O, CH4, and C2H2 concentration levels for >3 h indicated the stability of the reported multi-gas QEPAS sensor system.

Keywords

• Gas detection
• multi-component
• QEPAS sensor.