2009 JISAO/NCAS Research Internship
Laboratory studies of chlorine activation by nitrogen oxides
This summer I had the opportunity to venture out to the West Coast and work as a JISAO intern at the University of Washington in the Department of Atmospheric Sciences. As a Chemistry major at Morehouse College in Atlanta, I was quickly introduced to research, and by the second semester of my freshman year I secured a position in Professor Peter Chen's lab at Spelman College to work on A multi-wavelength multi-channel laser based method for detecting and monitoring nitrogen dioxide in air. Taking note of my interest in Atmospheric Science, I was glad to come across the JISAO internship that has allowed me to further explore the possibilities in this field.
Due to my prior undergraduate research with nitrogen dioxide, I was paired with Professor Joel Thornton who studies the daytime and nighttime chemistry of nitrogen oxide radicals. Under Professor Joel Thornton and graduate students in his lab, I was able to conduct Laboratory Studies of Chlorine Activation by Nitrogen Oxides.
The research I conducted was based on chemistry that occurs in the Marine Boundary Layer. Humans account for nearly 75% of all nitrogen oxide emissions in the world; in other words, the chemistry that I studied as a JISAO intern was, for the most part, human induced chemistry. The nitrogen oxides react with ozone to produce nitrate and nitrogen dioxide. The nitrogen dioxide (NO2) reacts again with nitrate to form dinitrogen pentoxide (N2O5) at equilibrium. At night, N2O5 reacts with aerosols containing Cl-, or better known as sea spray. Sea spray is the single largest source of atmospheric chloride. As N2O5 reacts with sea spray, nitryl chloride (ClNO2) is formed which is believed to cause the formation of chlorine atoms (Cl2) when reacted with aerosol particles with a pH of less than two.
The formation of Cl2 is very important because during the daytime, Cl2 is broken apart into two chlorine atoms. These chlorine atoms affect the lifetime of volatile organic compounds, including the greenhouse gas methane and they enhance the rate of ozone production in polluted surface air that results in degraded air quality. The main goals of my research were to study the heterogeneous chemistry of N2O5 and ClNO2 and to see if Cl2 could be produced from ClNO2 reacting with aerosols with a pH less than two.
To mimic the process that occurs every night on the coast, aerosols were created through an atomizer and then allowed to flow into a reaction tube. In the reaction tube, ClNO2 was introduced so that the reaction could occur. The resulting products of the gases were then sent through the chemical ion mass spectrometer (CIMS) where the number of each molecule present was counted. From my studies, I was able to conclude that Cl2 is produced from the reaction of ClNO2 on aerosol phase chloride, a process that had never been completed in the lab before, and that the ClNO2 to Cl2 reaction may be an equilibrium process.
The time I spent at the University of Washington as a JISAO intern offered me not only the chance to explore an area of science that I had always been interested in, but also a chance to explore the beautiful city of Seattle. I would like to thank JISAO for providing a wonderful experience and my mentor Joel Thornton for allowing me to become an active member in his research lab.