Spectroscopy and excited state dynamics of aromatic species relevant to the atmosphere of Titan
Abstract
The chemical evolution that occurs in the atmosphere on Titan is a complex and relatively unknown process. In the last 10 years, great advances have been made in understanding the conditions and composition of this unique body. In this work, we endeavor to add to the body of understanding to the atmosphere of Titan. Here we present the photo and discharge induced chemistry of two small molecules found in Titan's atmosphere: butadiene and vinylacetylene. In these studies, we observed the generation of many aromatic molecules, including the previously uncharacterized phenylcyclopentene and phenylcyclopentadiene. Once identified, the vibrationally resolved electronic spectroscopy of these two species was characterized. These molecules are deceptively similar as the competition between stabilization due to conjugation and steric hindrance leads to vastly different electronic structure, which was analyzed to yield molecular geometries and potential energy surfaces of several vibrational modes. The electronic spectroscopy of two molecules on the C10H 8 potential energy surface have also been characterized in this work: E and Z-phenylvinylacetylene (PVA). The electronic spectroscopy of PVA has been analyzed, as before, to determine the geometry of the ground and first excited states of the molecule and potential energy surface of the phenylvinyl torsional mode. This work served as the basis for further work to better understand the dynamics that govern the C10H8 potential energy surface. To this end, ultraviolet population transfer (UVPT) spectroscopy was developed in this work to elucidate the excited state isomerization. Using this newly developed method, along with fluorescence spectroscopy and the double-resonant technique of ultraviolet depletion spectroscopy, it was possible to create a near complete picture of the excited state dynamics of PVA.
Degree
Ph.D.
Advisors
Zwier, Purdue University.
Subject Area
Physical chemistry
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