Retrieval of Monocyclic Aromatic Hydrocarbons with Differential Optical Absorption Spectroscopy
XIE Pin-hua1, FU Qiang2, LIU Jian-guo1, LIU Wen-qing1, QIN Min1, LI Ang1, LIU Shi-sheng1, WEI Qing-nong1
1. Key Lab of Environmental Optics and Technology, Chinese Academy of Sciences, and Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China 2. China National Environmental Monitoring Center, Beijing 100029, China
Abstract：Differential optical absorption spectroscopy (DOAS) technique has been used to measure trace gases in the atmosphere by their strongly structured absorption of radiation in the UV and visible spectral range, e.g. SO2, NO2, O3 etc. However, unlike the absorption spectra of SO2 and NO2, the analysis of aromatic compounds is difficult and strongly suffers from the cross interference of other absorbers (Herzberg bands of oxygen, ozone and sulfur dioxide), especially with relatively low concentrations of aromatic compounds in the atmosphere. In the present paper, the DOAS evaluation of aromatic compounds was performed by nonlinear least square fit with two interpolated oxygen optical density spectra at different path lengths and reference spectra of ozone at different temperature and SO2 cross section to correct the interference from absorbers of O2, O3 and SO2. The measurement of toluene, benzene, (m,p,o)xylene and phenol with a DOAS system showed that DOAS method is suitable for monocyclic aromatic compounds monitoring in the atmosphere.
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