During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of sy...During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.展开更多
A dual-gas sensor system is developed for CO and CO_2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing(TDM) technique. A stepper motor based rotating system and a ...A dual-gas sensor system is developed for CO and CO_2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing(TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode(without rotation) and dynamic mode(with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million(ppm) in volume and 2.6 ppm for CO and CO_2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO_2, respectively. The reported sensor has potential applications in various fields requiring CO and CO_2 detection such as in the coal mine.展开更多
文摘During the measurement of atmospheric nitrate radical by long-path differential optical absorption spectroscopy, water vapor strong absorption could affect the measurement of nitrate radical and detection limits of system. Under the tropospheric condition, the optical density of water vapor absorption is non-linearly dependent on column density. An effective method was developed to eliminate the effect of water vapor absorption. Reference spectra of water vapor based on the daytime atmospheric absorption spectra, when fitted together with change of cross section with water vapor column densities, gave a more accurate fitting of water vapor absorptions, thus its effect on the measurements of nitrate radical could be restricted to a minimum and detection limits of system reached 3.6 ppt. The modified method was applied during an intensive field campaign in the Pearl River Delta, China. The NO3 concentration in polluted air masses varied from 3.6 ppt to 82.5 ppt with an average level of 23.6±1.8 ppt.
基金supported by the National Key R&D Program of China(Nos.2016YFD0700101 and 2016YFC0303902)the National Natural Science Foundation of China(Nos.61775079,61627823 and 61307124)+3 种基金the Science and Technology Planning Project of Guangdong Province,China(No.2017A020216011)the Science and Technology Development Program of Jilin Province,China(No.20140307014SF)the Industrial Innovation Program of Jilin Province,China(No.2017C027)Changchun Municipal Science and Technology Bureau,China(No.14KG022)
文摘A dual-gas sensor system is developed for CO and CO_2 detection using a single broadband light source, pyroelectric detectors and time-division multiplexing(TDM) technique. A stepper motor based rotating system and a single-reflection spherical optical mirror are designed and adopted for realizing and enhancing dual-gas detection. Detailed measurements under static detection mode(without rotation) and dynamic mode(with rotation) are performed to study the performance of the sensor system for the two gas samples. The detection period is 7.9 s in one round of detection by scanning the two detectors. Based on an Allan deviation analysis, the 1σ detection limits under static operation are 3.0 parts per million(ppm) in volume and 2.6 ppm for CO and CO_2, respectively, and those under dynamic operation are 9.4 ppm and 10.8 ppm for CO and CO_2, respectively. The reported sensor has potential applications in various fields requiring CO and CO_2 detection such as in the coal mine.
