Abstract
A highly sensitive carbon monoxide (CO) trace gas sensor based on quartz-enhanced photoacoustic spectroscopy (QEPAS) was demonstrated. A high-power distributed feedback (DFB), continuous wave (CW) 2.33 μm diode laser with an 8.8 mW output power was used as the QEPAS excitation source. By optimizing the modulation depth and adding an optimum micro-resonator, compared to a bare quartz tuning fork (QTF), a 10-fold enhancement of the CO-QEPAS signal amplitude was achieved. When water vapor acting as a vibrational transfer catalyst was added to the target gas, the signal was further increased by a factor of ~7. A minimum detection limit (MDL) of 11.2 ppm and a calculated normalized noise equivalent absorption (NNEA) coefficient of 1.8 × 10−5 cm−1W/√Hz were obtained for the reported CO-QEPAS sensor.
Highlights
Carbon monoxide (CO) is an air pollutant that is produced by incomplete production combustion activities, such as combustion of natural gas, fossil fuels and other carbon-containing fuels for power generation, petrochemical refining and vehicle or truck transportation
A quartz-enhanced photoacoustic spectroscopy (QEPAS)-based sensor for CO detection employing a 4.6 μm quantum cascade laser (QCL) as the excitation source was reported in Refs. [24,25]
The strongest absorption line could be targeted and a high excitation power can be achieved when employing a QCL, such CO-QEPAS sensor systems suffer from high cost, high power consumption and size
Summary
Carbon monoxide (CO) is an air pollutant that is produced by incomplete production combustion activities, such as combustion of natural gas, fossil fuels and other carbon-containing fuels for power generation, petrochemical refining and vehicle or truck transportation. A QEPAS-based sensor for CO detection employing a 4.6 μm quantum cascade laser (QCL) as the excitation source was reported in Refs. The strongest absorption line could be targeted and a high excitation power can be achieved when employing a QCL, such CO-QEPAS sensor systems suffer from high cost, high power consumption and size. The diode laser can access first overtone absorption band of CO, located at 2.3 μm, and diode laser-based CO-QEPAS sensors have been reported previously in Refs. An important feature of QEPAS is that the performance of QEPAS-based sensors can be improved when the excitation laser power is increased [28], since QEPAS detection sensitivity scales linearly with excitation laser power P (see Equation (1)). To date, commercially available 2.3 μm diode lasers have a maximum output power of ~2 mW, which limits the CO-QEPAS sensor performance. Enhancement of the CO-QEPAS signal was realized by the addition of water vapor to improve the CO vibrational-translational relaxation rate
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
