Date of Award

12-2013

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Physics

Major Professor

Robert N. Compton

Committee Members

Stuart Elston, Joseph H. Macek, Adam Petrie

Abstract

The existence of an additional electron or hole in the presence of an electric monopole is a well understood physical system, but this ideality is far from the true physical properties of many molecules. Examples of such irregular electronic states include the attachment of an excess charge to a molecule's dipole moment, electronic correlation spanning a molecule, or attachment of multiple excess charges. Current theoretical and experimental interpretations widely vary for these states and further elucidation of the nature of irregular electronic structure may provide solutions to unexplained observations and the impetus for industrial application. For example, in the case of dipole-bound electrons, it has been proposed that high-dipole moment molecules will attach electrons through the dipole moment which is then captured in to a valence state. In order to test this hypothesis, dipolar electron attachment to para-Nitroaniline is investigated. In addition, electron correlation within highly symmetric molecules may play a role in silenced photoionization and provide insight in to so called "super-excited" states or "collective excitations". In pursuit of this electronic character, we use the complex multi-photon ionization of tetrakis(dimethylamino)ethylene to study the possibility of collective electronic excitations. For this purpose, a hemispherical energy analyzer was adapted to acquire photoelectron spectra. Also, the presence of multiple excess charge stabilized on a molecule demands the presence of a stabilizing factor such as the repulsive coulomb barrier. In order to ascertain evidence for such stabilizing factors, we use collisional charge transfer between 7,7,8,8-tetracyanoquinodimethane and sodium for which a threshold would provide a metric of stability (electron affinity). Finally, we introduce Bayesian methods in the context of non-linear regression of collisional cross-sections (dissociative and charge-transfer) to address issues involved in the stability in the numerical estimations of partial derivatives. With this series of experiments we hope to shed new light on several types of irregular electronic states as well as to introduce the use of novel statistical methods.

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