The chemical mechanism of the limonene ozonolysis reaction in the SOA formation: A quantum chemistry and direct dynamic study

The ozonolysis of limonene is one of the most important processes for secondary organic aerosol formation and a detailed understanding of the atmospheric chemistry of d-limonene is highly urgent. In this paper, the reaction of d-limonene with O-3 has been studied using high level molecular orbital theory. A detailed description of the possible ozonolysis mechanism in the presence of H2O or NO is provided. The main products obtained are keto-limonene, limononic acid and 7OH-lim, which are low vapor pressure compounds. On the basis of the quantum chemical information, the direct dynamic calculation is performed and the rate constants are calculated over a temperature range of 200 similar to 800 K using the transition state theory and canonical varitional transition state theory with small-curvature tunneling effect. The four-parameter formula of rate constants with the temperature is fitted and the lifetimes of the reaction species in the troposphere are estimated according to the rate constants, which can provide helpful information to the model simulation study. (C) 2011 Elsevier Ltd. All rights reserved.