Production of highly oxidized organic compounds from ozonolysis of beta-caryophyllene: laboratory and field measurements

We conducted a laboratory investigation to identify highly-oxidized organic compounds formed in sesquiterpene (C15H24, SQT) ozonolysis. The dominant sesquiterpene previously identified from branch emissions of Scots pine, beta-caryophyllene, was used for this study. Using the latest mass spectrometric methods, we identified several highly oxidized organic compounds corresponding to RO2 radical, closed-shell monomer and dimer species. The most abundant compounds detected were monomers C15H24O7.9.11, and C15O22O9.11, and dimers C29H46O12.14.16, and C30H46O12,14,16, These oxidized organic compounds have very low saturation vapour pressures, an O-to-C ratio of about 0.3-0.9, and they are all classified as extremely low-volatility products (ELVOC). The molar yield of ELVOC was determined to be 1.7% +/- 1.28%. Highly-oxidized organic compounds were also measured at a boreal forest site, and few possible beta-caryophyllene oxidation products were identified, but the concentrations were extremely low, reaching a maximum of a few hundred thousand molecules cm(-3) in spring.