Date of Award

Spring 2013

Document Type

Thesis

Terms of Use

© 2013 Victoria P. Barber. All rights reserved. This work is freely available courtesy of the author. It may only be used for non-commercial, educational, and research purposes. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Chemistry & Biochemistry Department

First Advisor

Josh J. Newby

Abstract

The molecular structure of anethole (methoxy-4-(prop-l-enyl)benzene), was investigated using Jet-Cooled UV spectroscopy. A laser-induced fluorescence spectrum was obtained of the S₁-S₀ transition. Two 0⁰₀ transitions were observed in the LIF spectrum, separated by 69 cm⁻¹, and were assigned to the syn and anti conformers of anethole. Single vibronic level fluorescence spectra were obtained for both of the origin transitions. Bands of the S|VLF spectrum of each conformer were assigned by comparison with theoretical calculations at the DFT/B3LYP, 6-311G++(d,p) level of theory, as well as experimental information from similar molecules. In order to assign the LIF spectrum further, SVLF spectra were obtained of many of the LIF transitions, and assigned where possible. SVLF transitions of particular importance are the 63⁰₂ and the 39⁰₁ which appear reliably in almost all SVLF spectra, but at slightly different frequencies for each conformer, allowing the assignment of SVLF spectra to a specific conformation of anethole. LIF and SVLF data indicated the possibility of water-anethole van der Waals clusters, which were confirmed by adding water to the jet. Additionally, we performed potential energy scans of the vinyl and methoxy rotations of anethole, and fit these scans in order to determine parameters for anharmonicity and the barrier to rotation. By comparing to experimental fits in the literature, we determined that MP2 calculations predicted the barrier to rotation best, but HF calculations did a better job of predicting the anharmonicity. Opportunities for future work include the modeling of the potential using experimental data, further investigation of anethole-water clusters, finishing the assignment of the LIF and SVLF, and possibly investigating the spectroscopy of cis-anethole.

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