A reinvestigation of low molecular weight components in SOA produced by cyclohexene ozonolysis

The ozonolysis of cyclohexene is an important model system for understanding the more complex reaction of O3 with monoterpenes; however, many previous studies have come to qualitatively different conclusions about the composition of the secondary organic aerosol (SOA) formed in this system. In the present study, the composition of the SOA produced by cyclohexene ozonolysis in the absence of seed aerosols has been investigated online and off-line using synchrotron-based thermal desorption/tunable vacuum ultraviolet photoionization time-of-flight aerosol mass spectrometry (TD-VUV-TOF-PIAMS) in conjunction with a custom-built smog chamber. On the basis of the molecular ions observed by mass spectrometry at 11.5 eV, it was found that dicarboxylic acids, dialdehydes, and cyclic anhydrides are the predominant low molecular weight components in the particle phase. The results also indicated that TD-VUV-TOF-PIAMS coupled with filter sampling is a potentially useful tool for the investigation of SOA composition both in the field and in the laboratory.