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Title: Spectroscopy and dynamics of fluorescent protein chromophores and their molecular motifs
Author: Woodhouse, Joanne
ISNI:       0000 0004 7970 6400
Awarding Body: UCL (University College London)
Current Institution: University College London (University of London)
Date of Award: 2019
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Two experimental techniques, time-resolved photoelectron spectroscopy (TR-PES) of neutral molecules in a molecular beam and electrospray anion photoelectron spectroscopy (PES), have been combined with quantum chemistry calculations in an investigation of the electronic structure and excited state dynamics of biological fluorophores isolated in the gas-phase. Chapter 1 details the dynamics which may occur following photoexcitation of polyatomic molecules and explains what information can be gained about these excited-state dynamics using PES and velocity-map imaging. Chapter 2 provides the technical details of the experimental apparatuses, data analysis methods and quantum chemistry calculations used in this work. Chapter 3 presents a PES study of phenol, a molecular motif of the fluorophore of GFP and firefly luciferin. Femtosecond 1+1 REMPI spectra in the range 275 nm - 200 nm are presented for phenol, 2,6-dimethoxyphenol and 2,6-difluorophenol to examine the effect of these substituents on the electronic structure and dynamics of phenol. TR-PES at 236.5 nm is used to investigate excited-state O-H bond fission in the range of the S₂ electronic excited state. Chapter 4 presents nanosecond photoelectron spectra in the range 364 nm - 310 nm of phenolate, 2,6-dimethoxyphenolate and 2,6-difluorophenolate. While methoxy substituents have little effect on the electronic structure, the change in molecular geometry strongly influences the angular distribution of photoelectrons. Chapters 5 and 6 present detailed nanosecond PES studies of substituted GFP chromophore anions and an additional indirect detachment process via the Feshbach resonant 2ππ∗ state is assigned. In Chapter 7, the fi rst gas-phase PES study of the firefly luciferin anion and a redshifted variant, the infraluciferin anion, is presented in the range 357 nm - 230 nm. Both anions undergo resonant autodetachment processes via the S₃/ππ∗ state, and the infraluciferin anion also undergoes decarboxylation via the same state. Chapter 8 summarises the work presented in this thesis and proposes future experiments in this research area.
Supervisor: Fielding, H. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available