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Title: Investigating photo-induced bond breaking and making in solution phase aromatic molecules via ultrafast transient absorption spectroscopy
Author: Harris, Stephanie
ISNI:       0000 0004 5923 8208
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2015
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This thesis details ultrafast absorption spectroscopy studies of photo-induced processes in solution phase aromatic molecules. Application of this technique to the systems detailed below, using both a broadband infrared (IR) and/or ultraviolet (UV)/visible probe, has allowed the key species created directly by photo-excitation and subsequent processes to be identified as well as their transient behaviour to be followed. Kinetic and mechanistic information on the process or reaction is obtained, adding to both the understanding of the underlying photo-physics that drive the process in addition to the transient behaviour of the process itself. The systems investigated are; the UV photodissociation of phenol, the photo-Claisen and photo-Fries rearrangement of allyl phenyl ether and phenyl acetate respectively all in cyclohexane solvent, and three Paterno-Bilchi reactions between c),clohexene, furan or 2,3- dihydrofuran. The photodissociation of phenol in cyclohexane was studied by transient vibrational absorption spectroscopy. The spectra obtained supp0l1ed the results of a previous study of the photodissociation of phenol in solution using transient electronic absorption which found that the mechanism of photodissociation of phenol in a weakly interacting solvent remained the same as observed in the gas phase. Additionally, solution phase specific processes were observed following dissociation, such as recombination. Study of the photo-Claisen and photo-Fries rearrangements in solution using both transient absorption techniques allowed kinetic and mechanistic information on these processes to be obtained including rate coefficients for individual processes and quantum yields for the competing processes that determine the fate of the produced radical pair; solvent cage escape, recombination to form a cyclohexadienone of the original So product. The Paterno-Bilchi reactions between benzaldehyde and three solvents were also investigated. The first studied was the reaction with cyclohexene. This study proved that the biradical intermediates in this reaction along with other key species could be identified using these techniques. The subsequent study of the Paterno-Bilchi reaction with furan and 2,3- dihydrofuran investigated more detailed facets of this reaction.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available