Electronic Theses and Dissertations

Date of Award

1-1-2025

Document Type

Dissertation

Degree Name

Ph.D. in Chemistry

First Advisor

Ryan C. Fortenberry

Second Advisor

Eden E.L. Tanner

Third Advisor

Gregory S. Tschumper

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

Mechanistic and spectroscopic data for small astronomically-relevant molecules are necessary to make sense of astrophysical observations and modeling results. For certain groups of species, including cyclopropenylidenes, silica, silicates, and ortho-benzyne derivatives, more small-scale astrochemical insights are needed to bridge the gap between atoms and small molecules and larger structures. As these understudied species are among those that can be difficult to study experimentally, quantum chemistry provides an excellent medium for carrying out such work. Within this dissertation, elucidation of reaction pathways, qualitative and quantitative rate predictions, and computation of rovibrational spectroscopic data are combined in order to better understand the roles these species play in circumstellar and interstellar chemistry. Several cyclopropenylidene derivatives are presented as targets for interstellar detection, as are the ortho-benzyne derivatives biphenylene and benzopentalene. The early stages of circumstellar silica and magnesium silicate formation are outlined, producing precursors for the formation of larger species via nucleation. The achieved results also aim to make predictions regarding the chemical inventory of the universe, such as the reason for the absence of MgH beyond stellar atmospheres. Collectively, this work represents a major step forward in understanding the processes that drive cosmic evolution on the smallest of scales.

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