Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published November 18, 2004 | Supplemental Material
Journal Article Open

Low-Molecular-Weight and Oligomeric Components in Secondary Organic Aerosol from the Ozonolysis of Cycloalkenes and α-Pinene


The composition of secondary organic aerosol (SOA) from the ozonolysis of C_5−C_8 cycloalkenes and α-pinene, as well as the effects of hydrocarbon precursor structure and particle-phase acidity on SOA formation, have been investigated by a series of controlled laboratory chamber experiments. A liquid chromatography−mass spectrometer and an ion trap mass spectrometer are used concurrently to identify and to quantify SOA components with molecular weights up to 1600 Da. Diacids, carbonyl-containing acids, diacid alkyl esters, and hydroxy diacids are the four major classes of low-molecular-weight (MW < 250 Da) components in the SOA; together they comprise 42−83% of the total SOA mass, assuming an aerosol density of 1.4 g/cm^3. In addition, oligomers (MW > 250 Da) are found to be present in all SOA. Using surrogate standards, it is estimated that the mass fraction of oligomers in the total SOA is at least 10% for the cycloalkene systems (with six or more carbons) and well over 50% for the α-pinene system. Higher seed particle acidity is found to lead to more rapid oligomer formation and, ultimately, to higher SOA yields. Because oligomers are observed to form even in the absence of seed particles, organic acids produced from hydrocarbon oxidation itself may readily promote acid catalysis and oligomer formation. The distinct effects of carbon numbers, substituent groups, and isomeric structures of the precursor hydrocarbons on the composition and yield of SOA formed are also discussed.

Additional Information

© 2004 American Chemical Society. Received: June 11, 2004; In Final Form: August 30, 2004. This work was supported by U.S. Department of Energy Biological and Environmental Research Program DE-FG03-01ER63099, Electric Power Research Institute, and U.S. Environmental Protection Agency RD-83107501-0. We thank Jiwen He, Kee-Yoon Yoo, and Athanasios Nenes for assistance with calculating pH values of seed aerosols used in the α-pinene ozonolysis experiments. J. L. Beauchamp and R. Hodyss are acknowledged for their help with the use of ion trap mass spectrometry.

Attached Files

Supplemental Material - jp047466esi20040830_023400.pdf


Files (41.9 kB)
Name Size Download all
41.9 kB Preview Download

Additional details

August 19, 2023
October 23, 2023