光学学报, 2017, 37 (9): 0901001, 网络出版: 2018-09-07
基于腔衰荡光谱技术测量夜间大气中五氧化二氮 下载: 1034次
Measurement of Nitrogen Pentoxide in Nocturnal Atmospheric Based on Cavity Ring-Down Spectroscopy
大气光学 腔衰荡光谱技术 五氧化二氮 二极管激光 热解 atmospheric optics cavity ring-down spectral technology nitrogen pentoxide diode laser thermal decomposition
摘要
采用高温热解五氧化二氮(N2O5)的方法,利用N2O5与NO3自由基之间的热平衡关系,通过腔衰荡光谱技术测量N2O5及NO3自由基的浓度。基于二氧化氮(NO2)与N2O5之间平衡可逆,探讨加热温度及NO2浓度变化对N2O5分解率的影响;考虑N2O5在测量系统中的损耗,经初步的量化分析得到进气效率为88%。通过Allan方差选取最佳积分时间,在外场测量条件下,优化系统的体积分数探测限为8.6×10
-12;通过分析进气效率、吸收截面及N2O5不完全热解等不确定性因素,估算得到整体测量误差约为±10%。在合肥郊区进行夜间大气实际监测,测量期间N2O5的浓度变化范围在(0.035~1)×10
-9之间,平均浓度为4.52×10
-10。该技术为实现大气中N2O5及NO3自由基的高灵敏度在线监测提供了有效途径。
Abstract
Based on the thermal decomposition of nitrogen pentoxide (N2O5) and the thermal balance relationship between N2O5 and NO3 free radical, the concentrations of N2O5 and NO3 free radical are measured by cavity ring-down spectral technology. In view of the reversible balance between NO2 and N2O5, the influences of heating temperature and NO2 concentration on decomposition rate of N2O5 are investigated. Considering the loss of N2O5 in the measurement system, the inlet efficiency obtained by the preliminary quantitative analysis is about 88%. The optimum integration time is chosen according to the Allan variance, and the detection limit of volume fraction for the out-field observation is 8.6×10
-12. Considering the uncertainty of the inlet efficiency, absorption cross section and incompletion thermal decomposition of N2O5, the estimated total measuring error is about ±10%. A practical detection experiment for nocturnal atmosphere is carried out in Hefei. The N2O5 concentration ranges from 3.5×10
-11 to 1×10
-9 with a average value of 4.52×10
-10 during the measurement period. The proposed technique provides efficient way for realizing high sensivity on-line monitoring of N2O5 and NO3 free radical in ambient air.
王丹, 胡仁志, 谢品华, 刘小燕, 李治艳, 刘厚通, 黄仙山, 王东, 赵光兴. 基于腔衰荡光谱技术测量夜间大气中五氧化二氮[J]. 光学学报, 2017, 37(9): 0901001. Dan Wang, Renzhi Hu, Pinhua Xie, Xiaoyan Liu, Zhiyan Li, Houtong Liu, Xianshan Huang, Dong Wang, Guangxing Zhao. Measurement of Nitrogen Pentoxide in Nocturnal Atmospheric Based on Cavity Ring-Down Spectroscopy[J]. Acta Optica Sinica, 2017, 37(9): 0901001.