Acta Optica Sinica, Volume. 40, Issue 12, 1201003(2020)
Simultaneous Measurement of Nitrogen Dioxide and Organic Nitrate Based on Thermal Dissociation Cavity Ring-Down Spectroscopy
In this study, a two-channel thermal dissociation cavity ring-down spectroscopy (TD-CRDS) system based on cavity ring-down spectroscopy technology was established for the rapid and simultaneous measurement of ambient nitrogen dioxide (NO2) and organic nitrates (ON). NO2 was directly measured by its absorption at 406 nm, while ON was indirectly measured by the NO2 product of its thermal decomposition at 450 ℃. The ON conversion efficiency reached 99% at this temperature. The effective absorption cross-section of NO2 was obtained by the convolution of the high-resolution absorption cross-section of NO2 using a laser with a central wavelength of 406.02 nm. The laser spectrum was 5.74×10 -19 cm 2·molecule -1. A stability test of the heating device revealed an optimal flow rate of 1 L/min. The simultaneous measurement of the ambient NO2 by the NO2 and ON cavities exhibited good consistency, with the correlation coefficient R2=0.99. After optimization, the detection limit of the system reached up to 2.42×10 9 molecule·cm -3 (standard deviation: 3σ; temporal resolution: 1 s). Comparing the TD-CRDS system with the long-path differential optical absorption spectroscopy (LP-DOAS) in terms of NO2 measurement, good consistency was obtained (R2=0.93), indicating that the system has high measurement accuracy. The TD-CRDS system was applied to field observation, and the time series of NO2 and ON concentration were obtained.
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Chuan Lin, Renzhi Hu, Pinhua Xie, Shengyang Wu, Jinzhao Tong, Zhiyan Li, Fengyang Wang, Yihui Wang. Simultaneous Measurement of Nitrogen Dioxide and Organic Nitrate Based on Thermal Dissociation Cavity Ring-Down Spectroscopy[J]. Acta Optica Sinica, 2020, 40(12): 1201003
Category: Atmospheric Optics and Oceanic Optics
Received: Feb. 1, 2020
Accepted: Mar. 23, 2020
Published Online: Jun. 3, 2020
The Author Email: Lin Chuan (clin@aiofm.ac.cn), Hu Renzhi (rzhu@aiofm.ac.cn), Xie Pinhua (phxie@aiofm.ac.cn)