Browsing by Author "Yu, Ziwei"
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Item Probing Plasmon-Molecules Interactions with Surface-enhanced Raman Spectroscopy: Towards the Guided Design of Plasmonic Photocatalysts(2023-03) Yu, ZiweiPlasmonic materials have proven their strong candidacy as photocatalysts with their unique optical properties and strong interactions with light. The possibility of driving chemical reactions with sunlight to achieve high efficiency and selectivity has driven a lot of research exploring plasmonic photocatalysts. However, the progress has been slow due to a lack of mechanistic understanding. My thesis work aims to provide guidelines for plasmonic catalysts design through investigating plasmon-molecules interaction with various spectroscopic techniques.In this thesis, I will discuss my investigation of the energy transfer processes in the plasmonic-molecules systems on the ultrafast and steady state timescales with surface-enhanced Raman thermometry. Our results reveal that following the initial transient energy deposition, there is a quick energy dissipation between the molecules through intermolecular interactions on the ultrafast timescale (within 30 ps). On the steady state, surprisingly, we observed a “plasmon refrigerator” where the molecules are cooled below room temperature. In later work, I will discuss our work on developing surface-enhanced Raman optical activity spectroscopy and our investigation of the chiral interactions between molecules and plasmons. Our initial results suggest chirality transfer in the plasmonic-molecules systems. Lastly, I will propose a series of future directions to further the study of plasmon-molecules interactions. Herein, I show that surface-enhanced Raman spectroscopy (SERS) is a powerful technique, especially when coupled with other techniques such as Raman thermometry and Raman optical activity. Our studies on plasmon-molecules interactions will help with the development of plasmonic catalysis by providing guidelines for the design and optimization of plasmonic catalysts.Item Supporting data for Intermolecular Forces Dictate Vibrational Energy Transfer in Plasmonic–Molecule Systems(2022-02-22) Yu, Ziwei; Frontiera, Renee; rrf@umn.edu; Frontiera, ReneeThese files contain data along with associated output from described analysis supporting all results reported in Yu, Z.; Frontiera, R. R. Intermolecular Forces Dictate Vibrational Energy Transfer in Plasmonic–Molecule Systems. ACS Nano, 2022, 16, 1, 847–854. Anti-Stokes and Stokes scattering from aromatic thiols adsorbed on gold nanoparticles are monitored with ultrafast surface-enhanced Raman spectroscopy (SERS). Vibration population ratio changing kinetics of the aromatic thiols is obtained by conducting peak fitting with the acquired ultrafast anti-Stokes and Stokes SERS spectra and performing Boltzmann analysis. The as-obtained kinetic traces are fitted with exponential decay convoluted with the instrument response function to extract the temporal increase and lifetime of the population ratio kinetics, which are found to be correlated with the molecular property in a fashion that molecules with a stronger intermolecular interaction experience less temporal population ratio increase and shorter excited vibrational state lifetime.