Determination of discharge products using chirped-pulse Fourier transform microwave spectroscopy
Abstract
The purpose of this study is to study products generated in reactions initiated by an electric discharge. A chirped-pulse Fourier transform microwave (CP-FTMW) spectrometer is used as the molecular detector, allowing for discrimination between structural and conformational isomers. The ground state spectrum of methyl vinyl ketone is presented first to demonstrate the capabilities of the CP-FTMW instrument. Two conformers were identified and heavy atom isotopic species were observed in natural abundance. Furthermore, the presence of a methyl rotor resulted in A-E frequency splitting for each species that were clearly resolved in the microwave spectrum. The first set of discharge experiments included three different molecules and set out to characterize and optimize the additional parameters necessary with the discharge apparatus. The initial molecules of interest were 2,3- and 2,5-dihydrofuran because these isomers were known to have different decomposition reactions. It is shown that the discharge spectra for both molecules are unique and isomer-specific chemistry occurs for these molecules. There was also interest in conducting a bimolecular experiment, which led to studying the oxidation of 1,3-butadiene. Once these initial studies were complete, focus shifted to more environmentally relevant molecules. The next molecule studied was isoprene because it is the largest biogenic emission in the world and its atmospheric oxidation is an extremely important reaction. In addition to assigning previously known products, several new molecular species were observed in the reaction of isoprene and molecular oxygen. Another important area of environmental chemistry is the study of biofuels, such as butanol. Two isomers of butanol were studied, 1- and 2-butanol, to determine differences in reaction chemistry. There are unique molecular species observed in each discharge spectrum. This research demonstrates that CP-FTMW spectroscopy has distinct advantages for product determination of discharge chemistry and can be used to study a variety of molecules and reactions.
Degree
Ph.D.
Advisors
Dian, Purdue University.
Subject Area
Chemistry|Organic chemistry|Physical chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.