Particle mass yield in secondary organic aerosol formed by the dark ozonolysis of α-pinene J. E. Shilling1, Q. Chen1, S. M. King1, T. Rosenoern1, J. H. Kroll2, D. R. Worsnop2, K. A. McKinney3, and S. T. Martin1,4 1School of Engineering and Applied Sciences, Harvard Univ., Cambridge, MA 02138, USA 2Aerodyne Research, Inc., Billerica, MA 08121-3976, USA 3Dept. of Chemistry, Amherst College, Amherst MA 01002, USA 4Dept. of Earth and Planetary Sciences, Harvard Univ., Cambridge, MA 02138, USA
Abstract. The yield of particle mass in secondary organic aerosol (SOA) formed by dark
ozonolysis was measured for 0.3–22.8 ppbv of reacted α-pinene.
Most experiments were conducted using a continuous-flow chamber, allowing
nearly constant SOA concentration and chemical composition for several days.
For comparison, some experiments were also conducted in batch mode. Reaction
conditions were 25°C, 40% RH, dry (NH4)SO4 seed
particles, and excess 1-butanol. The organic particle loading was
independently measured by an aerosol mass spectrometer and a scanning
mobility particle sizer, and the two measurements agreed well. The
observations showed that SOA formation occurred for even the lowest reacted
α-pinene concentration of 0.3 ppbv. The particle mass yield was 0.09
at 0.15 μg m−3, increasing to 0.27 at 40 μg m−3.
Compared to some results reported in the literature, the yields were 80 to
100% larger for loadings above 2 μg m−3. At lower loadings,
the yields had an offset of approximately +0.07 from those reported in the
literature. To as low as 0.15 μm−3, the yield curve had no
inflection point toward null yield, implying the formation of one or several
products having vapor pressures below this value. These observations of
increased yields, especially for low loadings, are potentially important for
accurate prediction by chemical transport models of organic particle
concentrations in the ambient atmosphere.
Citation: Shilling, J. E., Chen, Q., King, S. M., Rosenoern, T., Kroll, J. H., Worsnop, D. R., McKinney, K. A., and Martin, S. T.: Particle mass yield in secondary organic aerosol formed by the dark ozonolysis of α-pinene, Atmos. Chem. Phys., 8, 2073-2088, doi:10.5194/acp-8-2073-2008, 2008.