Date on Master's Thesis/Doctoral Dissertation
12-2025
Document Type
Doctoral Dissertation
Degree Name
Ph. D.
Department
Chemistry
Degree Program
Chemistry, PhD
Committee Chair
Liu, Jinjun
Committee Member
Wilson, Andrew J.
Committee Member
Wittebort, Richard
Committee Member
Smadici, Serban
Author's Keywords
Laser; spectroscopy
Abstract
This dissertation examines the jet-cooled spectroscopy of the calcium propoxide radical (CaOC₃H₇) to understand how increasing molecular complexity reshapes symmetry, electronic degeneracy, and vibronic coupling. Moving from Ca–OCH₃ to Ca–OC₃H₇ lowers symmetry (C₃v → Cs → C₁) and exposes effects such as spin–orbit splitting and both Jahn–Teller and pseudo–Jahn–Teller distortions. These features remodel the excited-state potential surfaces and are directly observable with laser-induced fluorescence (LIF) and dispersed fluorescence (DF). A central goal is to evaluate whether CaOC₃H₇ supports the near-diagonal vibronic branching needed for efficient optical cycling, while also highlighting implications for catalysis and astrochemistry, where precise spectral fingerprints guide detection and mechanism building. LIF and DF spectra were recorded for the ò₁/ò₂ ← X̃² transition under supersonic cooling. Electronic excitation energies and vibrational frequencies for ground and excited states were computed using EOM-CCSD with the cc-pVTZ basis, and Franck–Condon (FC) simulations were performed to interpret band intensities. The data reveal both trans (T) and gauche (G) conformers. The splitting between the nearly degenerate Ã₁ and Ã₂ states is 77 cm⁻¹ (G) and 66 cm⁻¹ (T). Decomposition shows significant contributions from the electrostatic term ΔE₀—49.1 cm⁻¹ (G) and 30.8 cm⁻¹ (T)—and from spin–orbit coupling, with similar values of 59.3 cm⁻¹ (G) and 58.3 cm⁻¹ (T). Simulated FC matrices are predominantly diagonal, while modest off-diagonal intensity helps map vibronic interactions that influence optical cycling closure. Together, the measurements and calculations establish CaOC₃H₇ as a well-resolved testbed for direct laser cooling and as a source of high-fidelity spectra relevant to catalytic and interstellar environments.
Recommended Citation
Islam, Md Touhidul, "Spectroscopic studies of metal containing molecules under jet-cooled conditions using laster-induced fluoresence (LIF) and dispersed fluorescence (DF) techniques." (2025). Electronic Theses and Dissertations. Paper 4645.
Retrieved from https://ir.library.louisville.edu/etd/4645
