Access Type
Open Access Dissertation
Date of Award
January 2024
Degree Type
Dissertation
Degree Name
Ph.D.
Department
Chemistry
First Advisor
Aaron S. Rury
Abstract
The dissertation research focused on understanding the relationship between the chemical structure of organic molecules and their photophysical properties, particularly examining coherent electronic and vibrational coupling within and between molecules, with implications for next-generation energy technologies. In Chapter 2, we employed both steady-state and transient optical and magnetic spectroscopic techniques to understand the electronic delocalization in both singlet and triplet exciton delocalization in weakly bound porphyrin dimeric molecules. Our results highlight that the delocalization of singlet exciton delocalization does not guarantee the delocalization of triplet excitons between weakly bound porphyrin macromolecules. Our studies demonstrate how one can access the electronic delocalization of macromolecular systems central to the next-generation photochemical, photo-catalytic, and information-processing technologies using optical and magnetic spectroscopic techniques.
In Chapter 3, we investigated how strong light-matter coupling in porphyrin-based chromophores within Fabry-Pérot microresonators reduces the energetic disorder of excitons, crucial for integrating these materials into optoelectronic technologies. By studying cavity polaritons from distinct porphyrin dimers, we observed dispersive peak widths for lower polariton states, indicating potential enhancements in the coherence of hybrid molecular materials. Differences in excitonic disorder suppression among samples are attributed to microscopic light-matter interactions, particularly photonic exchange. Our findings highlight the potential of cavity polariton formation to enhance coherence in hybridmolecular materials, offering insights for future design strategies. In Chapter 4, we employed temperature-dependent Raman spectroscopy alongside density-functional theory calculations to investigate the anharmonic properties of 2-methylbenzimidazole. Our study aimed to understand how vibrations in this material contribute to the proton tautomerism (PT) mechanism responsible for ferroelectric switching. We developed a method based on standard anharmonic theory to analyze cubic and quartic couplings to low-frequency lattice vibrations, which affect intramolecular ring vibrations modulating carbon-nitrogen double bonds central to the PT mechanism. Our findings underscore the significance of vibrational spectroscopy in revealing how intermolecular interactions influence the structural dynamics of materials essential for sustainable information storage and nonlinear optical technologies.
Recommended Citation
Wanasinghe, S Mudiyanselage Sachithra Tikiri Kumara, "Probing Microscopic Properties Of Next Generation Materials Using Coherent Vibrational And Electronic Spectroscopy" (2024). Wayne State University Dissertations. 4046.
https://digitalcommons.wayne.edu/oa_dissertations/4046
