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Low‐Molecular Weight and Oligomeric Components in Secondary Organic Aerosol from the Photooxidation of p‐Xylene
Author(s) -
Huang MingQiang,
Zhang WeiJun,
Hao LiQing,
Wang ZhenYa,
Zhao WenWu,
Gu XueJun,
Fang Li
Publication year - 2008
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200800068
Subject(s) - aerosol , chemistry , aldehyde , mass spectrum , scanning mobility particle sizer , chemical composition , mass spectrometry , xylene , m xylene , hydrocarbon , mass fraction , particle (ecology) , analytical chemistry (journal) , particle size , photochemistry , particle size distribution , environmental chemistry , organic chemistry , chromatography , benzene , catalysis , oceanography , geology
A laboratory study was performed to investigate the composition of secondary organic aerosol (SOA) products from photooxidation of the aromatic hydrocarbon p‐xylene. The experiments were conducted by irradiating p‐xylene/CH 3 ONO/NO/air mixtures in a home‐made smog chamber. The aerosol time‐of‐flight mass spectrometer (ATOFMS) was used to measure the size and the chemical composition of individual secondary organic aerosol particles in real‐time. According to a large number of single aerosol diameters and mass spectra, the size distribution and chemical composition of SOA were determined statistically. Experimental results showed that aerosol created by p‐xylene photooxidation is predominantly in the form of fine particles, which have diameters less than 2.5 μm (i.e. PM2.5), and aromatic aldehyde, unsaturated dicarbonys, hydroxyl dicarbonys, and organic acid are major product components in the SOA after 2 hours photooxidation. After aging for more than 8 hours, about 10% of the particle mass consists of oligomers with a molecular mass up to 600 daltons. The possible reaction mechanisms leading to these products are also proposed.