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Title: Exploring excited state charge transfer and vibrational coherences with ultrafast spectroscopy
Author: Duchi, Marta
ISNI:       0000 0004 9358 9845
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2020
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The interaction between light and matter is a basic concept for the understanding of natural processes fundamental for all life on our planet. In the last three decades, femtochemistry has been developed to investigate the first steps of photoinduced reactions such as photochemistry or ultrafast DNA photoprotection mechanisms. In this thesis, the application of ultrafast techniques to three systems and the study of charge transfer mechanisms and vibrational coherences generated by ultrashort pulses is presented. A combined experiment of transient absorption and time-resolved infrared spectroscopies is used to investigate a model DNA composed of guanine and thymine, d(GpT). This study univocally demonstrates the formation of delocalised Franck-Condon excited state upon photoirradiation, which mediate a charge transfer mechanism with d(G+ pT- ) exciplex formation. In Chapter 5, the implementation of a state-of-the-art phase stable spectrometer which allows the acquisition of both broadband transient absorption and two-dimensional electronic spectroscopy data is presented. The setup is characterised by boxcar geometry and used to investigate the solvation dynamics of Oxazine 4 in different solvents. Data analysis reveals the generation of vibrational wave packets in both the ground and excited state of the dye in solution. Franck-Condon active modes are retrieved from the purely vibrational coherent spectra and assigned. From the comparison of frequency-frequency maps of Oxazine 4 in methanol and ionic liquid, a much slower recovery of the central line slope is observed when the ionic liquid surrounds the rigid dye. The solvation dynamics of zinc chlorin e6 in solution and inside a protein scaffold is also studied with broadband transient absorption spectroscopy. The ultrafast analysis reveals vibrational wave packets generated in the ground and excited state and a less efficient ability to “solvate” of the protein compared to conventional solvents.
Supervisor: Oliver, Tom Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available