EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Measurement of tropospheric HO2 radical using fluorescence assay by gas expansion with low interferences

Yihui Wang1,2, Renzhi Hu1, Pinhua Xie1, Fengyang Wang1,2, Jianguo Liu1, and Wenqing Liu1
Yihui Wang et al.
  • 1Key Laboratory of Environmental Optics and Technology, Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, Anhui, China (
  • 2School of Environmental Science and Optoelectronic Technology, University of Science and Technology of China, Hefei 230026, Anhui, China (

    An instrument to detect atmospheric HO2 radicals using fluorescence assay by gas expansion (FAGE) technique has been developed. HO2 is measured by reaction with NO to form OH and subsequent detection of OH by laser-induced fluorescence at low pressure. The system performance has been improved by optimizing the expansion distance and pressure, and the influence factors of HO2 conversion efficiency are also studied. The interferences of RO2 radicals produced from OH plus some typical organic compounds were investigated by determining the conversion efficiency of RO2 to OH during the measurement of HO2. The dependence of the conversion of HO2 on NO concentration was investigated, and low HO2 conversion efficiency was selected to realize the ambient HO2 measurement, where the conversion efficiency of RO2 derived by propane, ethene, isoprene and methanol to OH has been reduced to no more than 6%. Furthermore, no significant interferences from PM2.5 and NO were found in the ambient HO2 measurement. The detection limits for HO2 (S/N=2) are estimated to 4.8×105 cm-3 and 1.1×106 cm-3 (the conversion efficiency of HO2 to OH, =20%) under night and noon conditions, with 60s signal integration time. The instrument was successfully deployed during STORM-2018 field campaign at Shenzhen graduate school of Peking University. The diurnal variation of HOx concentration shows that the OH maximum concentration of those days is about 5.5×106 cm-3 appearing around 12:00, while the HO2 maximum concentration is about 5.0×108 cm-3 appearing around 13:30.

How to cite: Wang, Y., Hu, R., Xie, P., Wang, F., Liu, J., and Liu, W.: Measurement of tropospheric HO2 radical using fluorescence assay by gas expansion with low interferences, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12969,, 2020