Particle mass yield from β-caryophyllene ozonolysis

Abstract. The influence of second-generation products on the particle mass yield of β-caryophyllene ozonolysis was systematically tested and quantified. The approach was to vary the relative concentrations of first- and second-generation products by adjusting the concentration of ozone while observing changes in particle mass yield. For all wall-loss corrected organic particle mass concentrations M_org of this study (0.5 < M_org < 230 μg m⁻³), the data show that the particle-phase organic material was composed for the most part of second-generation products. For 0.5< M_org < 10 μg m⁻³, a range which overlaps with atmospheric concentrations, the particle mass yield was 10 to 20% and was not sensitive to ozone exposure, implying that the constituent molecules were rapidly produced at all investigated ozone exposures. In contrast, for M_org > 10 μg m⁻³ the particle mass yield increased to as high as 70% for the ultimate yield corresponding to the greatest ozone exposures. These differing dependencies on ozone exposure under different regimes of M_org are explained by a combination of the ozonolysis lifetimes of the first-generation products and the volatility distribution of the resulting second-generation products. First-generation products that have short lifetimes produce low-volatility second-generation products whereas first-generation products that have long lifetimes produce high-volatility second-generation products. The ultimate particle mass yield was defined by mass-based stoichiometric yields α_i of α₀ = 0.17 ± 0.05, α₁ = 0.11 ± 0.17, and α₂ = 1.03 ± 0.30 for corresponding saturation concentrations of 1, 10, and 100 μg m⁻³. Terms α₀ and α₁ had low sensitivity to the investigated range of ozone exposure whereas term α₂ increased from 0.32 ± 0.13 to 1.03 ± 0.30 as the ozone exposure was increased. These findings potentially allow for simplified yet accurate parameterizations in air quality and climate models that seek to represent the ozonolysis particle mass yields of certain classes of biogenic compounds.