光腔衰荡光谱法测量大气中的NO3和N2O5

本文应用基于二极管激光器的双路光腔衰荡光谱技术，分别对大气中NO₃和N₂O₅浓度进行监测. 通过使用实验室标准样校正有效吸收腔长比R_L和系统的总损耗系数?，并获得了NO₃有效吸收截面. 该装置在时间分辨率为1 s时，对NO₃的测量灵敏度达到1.1 pptv，N₂O₅被在线转换成NO₃，从而被另一路光腔衰荡光谱装置探测. 利用该装置，对合肥市区冬季夜间大气中的NO₃，N₂O₅浓度进行了实时监测. 通过对比一次大气快速清洁过程中氮氧化物、臭氧、PM_2.5等组分的浓度变化，讨论了大气环境下可能影响NO₃及N₂O₅浓度的因素.

Cavity Ring-Down Spectroscopy Measurements of Ambient NO3 and N2O5

NO₃ and N₂O₅ are important participants in nocturnal atmospheric chemical processes, and their concentrations are of great significance in the study of the mechanism of nocturnal atmospheric chemical reactions. A two-channel diode laser based cavity ring-down spectroscopy (CRDS) instrument was developed to monitor the concentrations of NO₃ and N₂O₅ in the atmosphere. The effective absorption length ratio and the total loss coefficient of the instrument were calibrated using laboratory standard samples. The effective absorption cross section of NO₃ at 662 nm was derived. A detection sensitivity of 1.1 pptv NO₃ in air was obtained at a time resolution of 1 s. N₂O₅ was converted to NO₃ and detected online in the second CRDS channel. The instrument was used to monitor the concentrations of NO₃ and N₂O₅ in the atmosphere of winter in Hefei in real time. By comparing the concentration changes of pollutants such as nitrogen oxides, ozone, PM_2.5 in a rapid air cleaning process, the factors affecting the concentrations of NO₃ and N₂O₅ in the atmosphere were discussed.