Sub-ppmv level detection of hydrogen sulphide(H_(2)S)using a 1.578-μm distributed feedback tunable diode laser combining with wavelength modulation spectroscopy and second harmonic detection scheme is reported.A home...Sub-ppmv level detection of hydrogen sulphide(H_(2)S)using a 1.578-μm distributed feedback tunable diode laser combining with wavelength modulation spectroscopy and second harmonic detection scheme is reported.A home-developed novel compact dense-pattern multipass gas cell with an effective optical path length of 29.37 m is used to improve sensitivity and reduce sample volume.Detection parameters are optimized,including modulation frequency and amplitude.The analysis of Allan variance shows that a minimum detectable concentration 60 ppbv is obtained with a lock-in time constant of 10 ms,and a detection limit of 13 ppbv can be achieved by average in 300 s.The demonstrated H_(2)S sensor has a strong penitential application in natural gas process for regulating and controlling H_(2)S concentration.展开更多
A compact and highly linear quartz-enhanced photoacoustic spectroscopy（QEPAS） sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork（QTF） is used as...A compact and highly linear quartz-enhanced photoacoustic spectroscopy（QEPAS） sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork（QTF） is used as the sharp transducer to convert light energy into an electrical signal based on the piezoelectric effect, thereby removing the need for a photodetector. The short optical path featured by the proposed sensing system leads to a decreased size. Furthermore, a pair of microresonators is applied in the absorbance detection module（ADM） for QTF signal enhancement. Compared with the system without microresonators, the detected QTF signal is increased to approximately 7-fold. Using this optimized QEPAS sensor with the proper modulation frequency and depth, we measure the water vapor concentration in the air at atmospheric pressure and room temperature. The experimental result shows that the sensor has a high sensitivity of 1.058parts-per-million.展开更多
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2016YFC0303900 and 2017YFC0209700)
文摘Sub-ppmv level detection of hydrogen sulphide(H_(2)S)using a 1.578-μm distributed feedback tunable diode laser combining with wavelength modulation spectroscopy and second harmonic detection scheme is reported.A home-developed novel compact dense-pattern multipass gas cell with an effective optical path length of 29.37 m is used to improve sensitivity and reduce sample volume.Detection parameters are optimized,including modulation frequency and amplitude.The analysis of Allan variance shows that a minimum detectable concentration 60 ppbv is obtained with a lock-in time constant of 10 ms,and a detection limit of 13 ppbv can be achieved by average in 300 s.The demonstrated H_(2)S sensor has a strong penitential application in natural gas process for regulating and controlling H_(2)S concentration.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61107070,61127018,and 61377071)
文摘A compact and highly linear quartz-enhanced photoacoustic spectroscopy（QEPAS） sensor for the measurement of water vapor concentration in the air is demonstrated. A cost-effective quartz tuning fork（QTF） is used as the sharp transducer to convert light energy into an electrical signal based on the piezoelectric effect, thereby removing the need for a photodetector. The short optical path featured by the proposed sensing system leads to a decreased size. Furthermore, a pair of microresonators is applied in the absorbance detection module（ADM） for QTF signal enhancement. Compared with the system without microresonators, the detected QTF signal is increased to approximately 7-fold. Using this optimized QEPAS sensor with the proper modulation frequency and depth, we measure the water vapor concentration in the air at atmospheric pressure and room temperature. The experimental result shows that the sensor has a high sensitivity of 1.058parts-per-million.
