关键词: 石英增强光声光谱/
量子级联激光器/
能级寿命
English Abstract
Research on high sensitivity detection of carbon monoxide based on quantum cascade laser and quartz-enhanced photoacoustic spectroscopy
Ma Yu-Fei1,2,He Ying1,
Yu Xin1,
Yu Guang1,
Zhang Jing-Bo1,
Sun Rui2
1.National Key Laboratory of Science and Technology on Tunable Laser, Harbin Institute of Technology, Harbin 150001, China;
2.Post-doctoral Mobile Station of Power Engineering and Engineering Thermophysics, School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China
Fund Project:Project supported by the National Natural Science Foundation of China (Grant No. 61505041), the Natural Science Foundation of Heilongjiang Province of China (Grant No. F2015011), the Special Financial Grant from the China Postdoctoral Science Foundation (Grant No. 2015T80350), the General Financial Grant from the China Postdoctoral Science Foundation (Grant No. 2014M560262), the Postdoctoral Fund of Heilongjiang Province, China (Grant No. LBH-Z14074), the Special Financial Grant from the Heilongjiang Province Postdoctoral Foundation of China (Grant No. LBH-TZ0602), the Fundamental Research Funds for the Central Universities of China (Grant No. HIT. NSRIF. 2015044), and the National Key Scientific Instrument and Equipment Development Projects of China (Grant No. 2012YQ040164).Received Date:20 October 2015
Accepted Date:25 December 2015
Published Online:05 March 2016
Abstract:Quartz-enhanced photoacoustic spectroscopy (QEPAS) technology was invented lately. Therefore it is an innovative method for trace gas detection compared with other existing technologies. In this paper, trace gas detection for carbon monoxide (CO) based on QEPAS technology is demonstrated. In order to realize high sensitive detection, a novel mid-infrared, state-of-art 4.6 m high power, continuous wave (CW), distributed feedback (DFB) quantum cascade laser (QCL) with single mode output is used as the laser exciting source. Therefore, the strongest absorption of fundamental frequency band of CO is achieved. Using the wavelength modulation spectroscopy and the 2nd harmonic detection, the influence of laser wavelength modulation depth on QEPAS signal level is investigated. Two important parameters of Q-factor and resonant frequency for quartz tuning fork as a function of gas pressure are measured. After optimization of the modulation depth of laser wavelength, the gas pressure of CO:N2 gas mixture and the improving speed of the V-R relaxation rate through the addition of water vapor, a minimum detection limit (MDL) of 1.95 parts per billion by volume (ppbv) for CO at gas pressure of 500 Torr and modulation depth of 0.2 cm-1 is achieved with a 1 sec acquisition time and the addition of 2.6% water vapor in the analyzed gas mixture. Finally, the influence of level lifetime of the targeted gas on QEPAS signal amplitude is investigated by comparison of CO QEPAS sensor performance using two different CO absorption lines of R(5) and R(6) located at 2165.6 cm-1 and 2169.2 cm-1respectively. The expression of the QEPAS signal amplitude is modified by adding the level lifetime parameter for a better precision.
Keywords: quartz-enhanced photoacoustic spectroscopy/
quantum cascade laser/
level lifetime
