Plasmonic nanomaterials have shown incredible promise for initiating photochemical reactions due to their strong and tunable optical cross sections. Upon irradiation, plasmonic materials focus incident irradiation to nanoscale volumes, generate a large number of energetic electrons and holes, as well as heat up surrounding media. It can be difficult to determine how these different physical effects contribute to photochemistry, as the energy partitioning processes following plasmon excitation occur on ultrafast timescales. In order to disentangle the effects of electromagnetic fields, hot carrier transfer, and heating on plasmon-driven chemical reactions, we have developed an ultrafast surface-enhanced Raman spectroscopic (SERS) technique to selectively probe ligands and adsorbates near the plasmonic nanomaterial surface. Ultrafast SERS provides the ability to monitor changes in reactants undergoing chemical conversion, as well as monitor vibrational temperatures through the acquisition of transient Stokes and anti-Stokes Raman spectra. In this talk, I’ll discuss how we have shown that heating is not a significant contributor to most plasmonic photocatalysis due to inefficient heating of molecular adsorbates, as well as present results on mode-specific energy deposition and hot carrier transfer. This ultrafast view of ligand protected nanoparticle chemistry is crucial for understanding the mechanism of plasmon-driven processes as well as guiding optimization of more efficient plasmonic catalysts.<br/>

Monitoring nanoparticle-driven chemistry with ultrafast surface-enhanced Raman spectroscopy

2019 Fall National Meeting

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