RUI: Kinetics and Products of Hydroxyl Radical (OH) and Chlorine (Cl) Reactions with High Molecular Weight Organic Aerosol Precursor Compounds

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Experimental investigations of the interactions between C8-C15 high molecular weight (MW) organic aerosol precursor compounds (OAPCs) and atmospheric oxidants will be conducted to help address issues concerning atmospheric organic aerosol chemistry. The objective of this project is to acquire rate constants and intermediate/product information at 220-300 K for reactions of Hydroxyl Radical (OH) and Chlorine (Cl) radicals with high MW OAPCs using the relative rate/discharge flow/mass spectrometry (RR/DF/MS) technique. This objective will be achieved through the following set of activities:1) Determination of rate coefficients for the reactions of OH and Cl with three to six high MW OAPCs under both low pressure and turbulent flow conditions at room temperature. Primary choices of high MW OAPCs include n-decane, n-undecane, n-dodecane, dodecylcyclohexane, decylcyclohexane, octanal, nonanal, decanal, octanoic acid, nonanoic acid, pinenes, anthracene, and naphthalene.2) Determination of rate constants for the reactions of OH and Cl with selected high MW OAPCs at temperature ranges representative of the troposphere (220-300 K). If the adsorption of high MW OAPCs onto the flow reactor significantly affects the kinetic results, the rate constants will be measured under turbulent flow conditions. Otherwise rate constants as a function of temperature will be determined under low-pressure conditions.3) Identification and quantification of the water and hydrocholoric acid products for the reactions under investigation, and determination of the branching ratio if the reaction has more than one pathway at 220-300 K.Results obtained from the proposed research will provide insight on the formation, growth, and oxidation of atmospheric organic aerosols, and improve current understanding of the impact of natural and anthropogenic emissions of high MW OAPCs on air quality. The kinetic and product data obtained from this project will add important new inputs to the existing database for atmospheric modeling involving organic aerosols.The broader impacts of this project will be primarily the significant positive impact on the research environment at California State University Fullerton (CSUF), which is a predominantly undergraduate institution. The project will lead to the training of high quality researchers and scientists at CSUF. Both graduate and undergraduate students involved in this project will be introduced to the frontiers of atmospheric chemistry and will be challenged to address both environmental and scientific questions raised during the research. They will also be exposed to and learn a variety of scientific methods and techniques, including operation and maintenance of a mass spectrometer, high vacuum systems, microwave discharge devices, and turbulent flows, plus kinetic and product data acquisition and analysis. Finally, they will participate in national and international meetings to present their results, and publish their results in peer-reviewed scientific journals.One educational goal of this research is to provide opportunities for junior and senior undergraduate students, especially those of underrepresented groups (minorities, females), to have tangible research experience in order to foster their interests in atmospheric and environmental chemistry.