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 Title: Size Effects On Excited State Lifetimes Of Titanium Oxide Clusters Author(s): Heald, Lauren F Contributor(s): Sayres, Scott G; Garcia, Jacob M Subject(s): Dynamics and kinetics Abstract: Transition metal oxides are widely used as catalysts for industrial processes. Notably, TiO$_{2}$ is used in applications such as water splitting, photovoltaics, and environmental degradation of organic pollutants. Despite the wide usage of TiO$_{2}$, there is not a clear understanding of the mechanism that underpins its reactivity. The study of ultrafast excitation/relaxation dynamics in neutral titanium oxide clusters offers atomic level insight into the driving forces in bulk reactions. Specifically, we utilize pump-probe spectroscopy to reveal the influence of both size and oxidation affect the excited state lifetimes of neutral metal oxides. All clusters exhibit a rapid relaxation lifetime of ~30 fs, followed by a sub-picosecond lifetime that we attribute to carrier recombination. The excited state lifetimes oscillate with size in agreement with the cluster stability, coordination of metal atoms, and localization of electron excitation. These experimental results, when paired with TD-DFT, demonstrate the importance of subtle changes in the atomic positions and geometry over the cluster dynamics. Such revelations relate directly to the significance of defect sites in bulk materials. This presentation will focus on both experimental and computational analysis of sub-nanometer TiO$_{2}$ clusters and how the lifetimes of excited states can be understood through analysis of electron/hole dynamics. A thorough discussion of how properties of neutral clusters change with the addition or subtraction of a single atom will be used to provide insight into the properties that make TiO$_{2}$ such a favorable material. Issue Date: 2021-06-24 Publisher: International Symposium on Molecular Spectroscopy Genre: Conference Paper / Presentation Type: Text Language: English URI: http://hdl.handle.net/2142/111534 Date Available in IDEALS: 2021-09-24
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