Yan, Han2024-01-242024-01-242023https://udspace.udel.edu/handle/19716/33902Photoinduced heterogeneous electron transfer (HET) is fundamentally important in many physical, chemical, and biological processes, with a wide range of applications such as photocatalysis, sensors, dye-sensitized solar cells, photolithography, and artificial photosynthesis. In photoinduced HET, a photoexcited electron is transferred from a molecular donor state to multiple acceptor states in a semiconductor. These reactions can occur on time scales as short as a couple of femtoseconds. ☐ In this dissertation, HET is studied with ultrafast spectroscopy on HET systems comprised of perylene derivatives that are covalently bound to colloidal TiO2 surfaces. Perylene chromophores have been chosen for their electronic and optical properties, making them ideal model systems. The specific focus of this work involves the manipulation of the conformation and chemical structure of the linker group that attaches the perylene chromophore to the TiO2 surface. Ultrafast spectroscopy was employed to gain insights into dynamics, electronic coupling, vibrational states, and various effects such as vibronic, structural, and binding effects. ☐ Transient absorption and pump-degenerate four-wave mixing were the primary ultrafast spectroscopies used to study HET and the vibrational response of the system. The experimental results were compared with theoretical simulations from collaborators and revealed the importance of electronic-vibrational coupling on HET. Perylene chromophores with systematic changes in the substitution position and number of linker groups were compared, yielding unexpected results that were explained by vibronic effects, binding effects, as well as conformational effects.PhotolithographyMolecular donor stateHeterogeneous electron transferUltrafast spectroscopyPerylene chromophoresThesis1428166503https://doi.org/10.58088/cjs2-bq382024-01-22en