FTIR Analysis of Aerosol Formed in the Ozone Oxidation of Sesquiterpenes

Abstract

ABSTRACT. A Low Pressure Impactor (LPI) was used to collect aerosol generated by the reactions of ozone with a -cedrene, a -copaene, b -caryophyllene, and a -humulene. The aerosol was generated in an environmental chamber and the chemical composition of the aerosol was examined using Fourier Transform Infrared Spectroscopy (FTIR). The relative molar concentrations of functional groups in the aerosol were estimated based on the infrared spectra and model compound calibrations. Ketones and aldehydes were the dominant functional groups in the aerosol-phase reaction products. Two to four carbonyl groups were present in average aerosol molecules. Hydroxyl groups were present in both carboxylic acid (0.2-0.7 groups per average molecule) and alcohol (0.5-1.3 groups per average molecule) structures. These structural characterizations of aerosol phase products were used to postulate chemical pathways for aerosol formation.

Characterisation of organic compounds in aerosol particles from a Finnish forest by on-line coupled supercritical fluid extraction?liquid chromatography?gas chromatography?mass spectrometry

“…It has been discussed whether or not the oxidation products of biogenic hydrocarbons play a crucial role in the new particle formation over forests [17,18,19,40,41,42]. The oxidation reactions typically involve ozonolysis of monoterpenes or sesquiterpenes, and the reaction products are usually more polar and have lower vapour pressures than the parent compounds.…”

Spatial and temporal distribution of atmospheric aerosols in the lowermost troposphere over the Amazonian tropical rainforest

“…The remaining fraction of the aerosol is largely composed of insoluble or partially water-soluble organics (Graham et al, 2003b), emphasising the importance of organic material in formation of the aerosol particles over the rain forest. Besides monoterpenes, other VOCs, for example sesquiterpenes, can also play important role in new particle formation due to their very fast oxidation with O 3 and OH radical (Bonn and Moortgat, 2003;Dekermenjian et al, 1999;Shu and Atkinson, 1995). Sesquiterpenes have been detected in the atmosphere during flux measurements in central Amazonia, however, the source strength and fate of the sesquiterpenes over the rain forest are virtually unknown (P. Ciccioli, Institute of Chemical Methodology, Italy; personal communication).…”

Theoretical study on mechanism for O3-initiated atmospheric oxidation reaction of β-caryophyllene

“…b-Caryophyllene aldehyde, b-nocaryophyllone aldehyde, and formaldehyde are identified as the main gaseous products [16,19]. Dekermenjian studies the particulate reaction products, and a relative molar concentration of functional groups is reported based on the infrared spectra [20]. Ketones and aldehydes are found to be the dominant functional groups in the particulate products [20].…”