Author ORCID Identifier
https://orcid.org/0009-0002-2078-5231
Defense Date
2025
Document Type
Dissertation
Degree Name
Doctor of Philosophy
Department
Chemistry
First Advisor
Katherine M. Tibbetts
Second Advisor
Maryanne Collinson
Third Advisor
Dusan Bratko
Fourth Advisor
Massimo Bertino
Abstract
This dissertation uncovers the ultrafast molecular mechanisms underlying the decomposition of nitrate ester explosives—nitroglycerin (NG), ethylene glycol dinitrate (EGDN), and amyl nitrate—through the integration of femtosecond time-resolved mass spectrometry and advanced computational chemistry. Although these compounds play fundamental roles in both military and civilian contexts, the precise molecular dynamics governing their pronounced reactivity and impact sensitivity have remained inadequately characterized. Our research establishes that low O–NO2 bond dissociation energies are the primary driver of ultrafast fragmentation and high reactivity in all three esters. The distinctive molecular architectures of these esters dictate their explosive properties: NG’s tri-nitrate configuration leads to exceptional energy release and high sensitivity; EGDN’s structure imparts notable low-temperature stability; and amyl nitrate’s singular nitrate group results in reduced energetic output but relevance for non-explosive applications. Fragmentation is shown to proceed predominantly via homolytic cleavage of nitrate groups, with mass spectrometric signatures closely reflecting the underlying molecular frameworks. Complementary density functional theory (DFT) calculations elucidate the electronic structure changes that accompany ionization and bond rupture, mapping key transition states and relative energetics. These computational predictions, benchmarked against experimental observables, enable molecular-level insight into reactivity, rate trends, and impact sensitivity for all three systems. Ab initio molecular dynamics (AIMD) simulations, performed in parallel with experiment, capture real-time dissociation trajectories following ionization. The timescales i and ii, and the primary fragmentation pathways observed in AIMD ensemble data, quantitatively agree with those extracted from femtosecond pump-probe experiments, providing strong concordance between theory and measurement and confirming the proposed mechanisms. The convergence of ultrafast experimental techniques and quantum-chemical modeling enables the formulation of robust structure–reactivity relationships, linking bond dissociation energies and key conformational motifs to macroscopic decomposition rates and sensitivities. These insights deepen fundamental understanding while also guiding the rational design of safer explosives and advanced propellants. This work pioneers femtosecond-resolved studies of nitrate ester dynamics and lays the groundwork for future explorations across broader families of energetic compounds.
Rights
© Erica Britt
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
12-11-2025
Included in
Analytical Chemistry Commons, Computational Chemistry Commons, Forensic Chemistry Commons, Physical Chemistry Commons