Campus Access Only

All rights reserved. This publication is intended for use solely by faculty, students, and staff of University of the Pacific. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

A tale of two small oxygenated molecules as told by photoelectron photoion coincidence spectroscopy

Author

Chrissa Michelle Mozaffari Easter, University of the Pacific

Date of Award

2016

Document Type

Thesis - Pacific Access Restricted

Degree Name

Master of Science (M.S.)

Department

Pharmaceutical and Chemical Sciences

First Advisor

Balint Sztaray

First Committee Member

Anthony Dutoi

Second Committee Member

Helene Flohic

Third Committee Member

Silvio Rodriguez

Abstract

Photoelectron Photoion Coincidence (PEPICO) Spectroscopy studies on two small oxygenated species are presented here. Diethyl Ether (Et2O) and Acetic Anhydride (AcOAc) were chosen because of their and their fragments' relevance to combustion chemistry. The Imaging PEPICO (iPEPICO) experiment at the VUV beamline of the Swiss Light Source (SLS) was utilized to provide dissociative ionization data of the two molecules of interest. In this experiment, the unimolecular fragmentation pathways of energy selected ions can be studied with high energy resolution. The iPEPICO experimental setup also allows the measurement of the dissociation rates, which is indispensable to derive accurate thermochemical information on large ions. The experimental data on the fragmentation of ions of interest are then examined through modeling the experimental ion fractional abundances (breakdown curves, BDCs) and reaction rates, in a modeling framework based on the RRKM statistical theory. In our first project, diethyl ether was studied to provide the appearance energies of its daughter ions along with the dissociation pathways of the molecular ion, leading to thermochemical data (such as heats of formation) pertinent to combustion chemistry. A revised ionization energy (IE) differing from the reviewed National Institute of Standards and Technology (NIST) was also proposed. In the second project presented, AcOAc was also measured on the iPEPICO apparatus to understand its dissociative photoionization processes. The appearance of trace amounts of acetone in the ionization spectra, discrepancies in the statistical models of the branching ratios, and the quantum chemical calculations all point to the existence of a post-transition-state bifurcation, when a single TS separates multiple products, namely a methyl-loss fragment and acetone, as well. The acetyl cation, as well as the methyl cation at higher energies, appear to be formed by both parallel and sequential dissociation processes.

Pages

87

ISBN

9781339848518

Recommended Citation

Easter, Chrissa Michelle Mozaffari. (2016). A tale of two small oxygenated molecules as told by photoelectron photoion coincidence spectroscopy. University of the Pacific, Thesis - Pacific Access Restricted. https://scholarlycommons.pacific.edu/uop_etds/263

Creative Commons License

This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.