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Published December 2001 | public
Journal Article

The effect of water on gas–particle partitioning of secondary organic aerosol: II. m-xylene and 1,3,5-trimethylbenzene photooxidation systems


An investigation of the effect of relative humidity on aerosol formation from in-xylene and 1,3,5-trimethylbenzene photooxidation is reported, Experiments were performed in the presence and absence of ammonium sulfate seed particles (both aqueous and dry) to ascertain the effect of partitioning of oxidation products into a strong electrolytic solution or onto dry crystalline seed particles, In marked contrast to the alpha -pinene/ozone system, the final measured secondary organic aerosol yield was unaffected by the presence of gas-phase or liquid-phase water at relative humidities (RH) up to 50%. The hygroscopic nature of the aerosol generated upon photooxidation of m-xylene and 1,3,5-trimethylbenzene was examined; the hygroscopicity of the aerosol at 85% RH for both parent organics increased with the extent of the reaction, indicating that the first-generation oxidation products undergo further oxidation. Limited identification of the gas- and aerosol-phase products of in-xylene and 1,3,5-trimethylbenzene photooxidation is reported, It is evident that a more complete molecular identification of aromatic photooxidation aerosol awaits analytical techniques not yet brought to bear on this problem.

Additional Information

This work was supported by the US Environmental Protection Agency Center on Airborne Organics, US Environmental Protection Agency Agreement CR827331-01-0, and the Chevron Corporation. David Cocker was supported in part by a NSF graduate fellowship. Special thanks to K.M. Cocker, N.E. Whitlock, H. Zhuang, and R. Bahreini.

Additional details

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October 23, 2023