Kinetics of Heterogeneous Reactions of HO2 Radical at Ambient Concentration Levels with (NH4)2SO4 and NaCl Aerosol Particles
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- 作者：Fumikazu Taketani ; Yugo Kanaya ; Hajime Akimoto
- 刊名：Journal of Physical Chemistry A
- 出版年：2008
- 出版时间：March 20, 2008
- 年：2008
- 卷：112
- 期：11
- 页码：2370 - 2377
- 全文大小：172K
- 年卷期：v.112,no.11(March 20, 2008)
- ISSN：1520-5215
文摘
The HO2 uptake coefficient (
) for inorganic submicrometer wet and dry aerosol particles ((NH4)2SO4 andNaCl) under ambient conditions (760 Torr and 296 ± 2 K) was measured using an aerosol flow tube (AFT)coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. The CC/LIF techniqueenabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere.HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position-dependentprofiles of LIF intensity were measured as a function of aerosol concentration. Measured values for dryaerosols of (NH4)2SO4 were 0.04 ± 0.02 and 0.05 ± 0.02 at 20% and 45% relative humidity (RH), respectively,while those of NaCl were <0.01 and 0.02 ± 0.01 at 20% and 53% RH, respectively. For wet (NH4)2SO4aerosols, measured values were 0.11 ± 0.03, 0.15 ± 0.03, 0.17 ± 0.04, and 0.19 ± 0.04, at 45%, 55%,65%, and 75% RH, respectively, whereas for wet NaCl aerosols the values were 0.11 ± 0.03, 0.09 ± 0.02,and 0.10 ± 0.02 for 53%, 63%, and 75% RH, respectively. Wet (NH4)2SO4 and NaCl aerosols doped withCuSO4 showed values of 0.53 ± 0.12 and 0.65 ± 0.17, respectively. These results suggest that compositions,RH, and phase for aerosol particles are significant to HO2 uptake. Potential HO2 loss processes and theiratmospheric contributions are discussed.
) for inorganic submicrometer wet and dry aerosol particles ((NH4)2SO4 andNaCl) under ambient conditions (760 Torr and 296 ± 2 K) was measured using an aerosol flow tube (AFT)coupled with a chemical conversion/laser-induced fluorescence (CC/LIF) technique. The CC/LIF techniqueenabled experiments to be performed at almost the same HO2 radical concentration as that in the atmosphere.HO2 radicals were injected into the AFT through a vertically movable Pyrex tube. Injector position-dependentprofiles of LIF intensity were measured as a function of aerosol concentration. Measured values for dryaerosols of (NH4)2SO4 were 0.04 ± 0.02 and 0.05 ± 0.02 at 20% and 45% relative humidity (RH), respectively,while those of NaCl were <0.01 and 0.02 ± 0.01 at 20% and 53% RH, respectively. For wet (NH4)2SO4aerosols, measured values were 0.11 ± 0.03, 0.15 ± 0.03, 0.17 ± 0.04, and 0.19 ± 0.04, at 45%, 55%,65%, and 75% RH, respectively, whereas for wet NaCl aerosols the values were 0.11 ± 0.03, 0.09 ± 0.02,and 0.10 ± 0.02 for 53%, 63%, and 75% RH, respectively. Wet (NH4)2SO4 and NaCl aerosols doped withCuSO4 showed values of 0.53 ± 0.12 and 0.65 ± 0.17, respectively. These results suggest that compositions,RH, and phase for aerosol particles are significant to HO2 uptake. Potential HO2 loss processes and theiratmospheric contributions are discussed.