Kinetics of the Hydroxyl Radical (OH) and Ozone-Initiated Oxidation of Biogenic Terpenes

Indiana University, Bloomington IN

Investigators

Abstract

The overall goal of this project is an improved understanding of the influence of biogenic emissions on atmospheric chemistry, through studies of the kinetics and mechanisms of the OH (hydroxyl radical) and ozone-initiated oxidation of isoprene and various terpenes, such as farnesenes, 4,8-dimethyl-1,3,7-nonatriene (DMNT), beta-myrcene, and beta-ocimene. These biogenic volatile organic compounds (BVOCs) have recently been identified in forests, and may be partially responsible for very rapid chemical reactions with atmospheric oxidants in these environments. Experiments will include measurements of rate constants for the reactions of these compounds with OH and ozone, direct measurements of the yield of OH radicals produced by ozonolysis of these compounds, and identification and quantification of some of the products. The experiments will use on-line mass spectrometry with relative rate techniques as well as discharge flow techniques with laser-induced fluorescence detection of OH. This study should lead to improved knowledge of the details of some of the oxidation mechanisms and will help to determine the efficiency of these BVOCs in the production of photochemical smog. The measurements will also help to determine whether biogenic emissions are a significant source of OH radicals both during the day and at night. The results of this project will have broader impacts on understanding the contribution of biogenic emissions to ozone and aerosol formation in the atmosphere. This project will also provide research and educational opportunities for graduate students and undergraduates, including several students from under-represented populations.