Acta Optica Sinica, Volume. 41, Issue 14, 1430003(2021)
Sensitive Detection of CH4 and CO2 Using Frequency-Division-Multiplexing Based Quartz-Enhanced Photoacoustic Spectroscopy
A compact double-gas sensing system was constructed for the simultaneous sensitive detection of CH4 and CO2,which combines quartz-enhanced photoacoustic spectroscopy (QEPAS) and frequency division multiplexing technique. Two continuous wave distributed feedback (DFB) diode lasers operating at central wavelengths of 1654 nm and 2004 nm were employed as the light sources. The photoacoustic signals were first excited by simultaneously injecting sinusoidal modulation currents with independent frequencies near the resonant frequency of the quartz tuning fork into the lasers, and were then demodulated to obtain the corresponding second harmonic components of CH4 and CO2,and finally the simultaneous detection of CH4 and CO2 was realized. The experimental results showed that there was no disturbance between the photoacoustic signals of these two gases. The relationships of CH4 and CO2 concentrations with their corresponding second harmonic signals were calibrated, and a good linear response result was obtained, in which the linear correlation coefficients were all larger than 0.994. The long time measurement of CH4 with volume fraction of 500×10-6 and CO2 with volume fraction of 2000×10-6 was conducted and the system performance was further evaluated through the Allan deviation analysis. The results indicated that the minimum detection limits of CH4 and CO2 for the system were obtained as 0.58×10-6 and 1.32 ×10-6, corresponding to the normalized noise equivalent absorption coefficients of 7.2×10-9 cm-1·W·Hz1/2 and 9×10-9 cm-1·W·Hz1/2, respectively.
Get Citation
Copy Citation Text
Hao Liu, Mai Hu, Xiang Chen, Hao Deng, Zhenyu Xu, Qiang Wang, Xiang Li, Ruifeng Kan, Xianyi Zhang. Sensitive Detection of CH4 and CO2 Using Frequency-Division-Multiplexing Based Quartz-Enhanced Photoacoustic Spectroscopy[J]. Acta Optica Sinica, 2021, 41(14): 1430003
Category: Spectroscopy
Received: Dec. 31, 2020
Accepted: Feb. 22, 2021
Published Online: Jul. 11, 2021
The Author Email: Kan Ruifeng (kanruifeng@aiofm.ac.cn), Zhang Xianyi (xyzhang@mail.ahnu.edu.cn)