Supplemental Funding for Summer Salary (CaSTL)

The Van Duyne group will contribute to the thrust focusing on plasmon driven chemistry and photoelectron emission. Our technical innovation is the use ultrafast spectroscopy at noble metal STM tips to study plasmon-driven chemistry with high spatial and temporal resolution. The primary research interest of the Van Duyne group in the center is in site specific electron transport dynamics and proton coupled electron transfer (PCET) reactions. We will initially work with the following systems: electron transfer to Ru(bpy)3+2, Os(bpy)3+2,PCET in ruthenium and osmium aquo complexes, and 4-mercaptopyridinium mediated CO2 reduction. These species will be tethered to Au or Ag plasmonic surfaces using mixed monolayer alkanethiol chemistry and monitored using ultrafast tip-enhanced Raman spectroscopy (TERS). Specific example systems are [Ru(bpy)2(4-aminomethylpyridine)(H2O)]2+ or the osmium analog [Os(bpy)2(4-aminomethylpyridine)(H2O)]2+ bonded to HS(CH2)nCOOH. Varying the length of the tether (n = 6-15) to the surface will allow the electron transport events to be understood in the presence of plasmonic structures. It should be noted that unlike SERS which is limited by its distance dependence to n = 6-11, TERS should be able to probe the entire n = 6-15 range. This research has potential for a number of collaborations within the center. Experiments will be performed by the Van Duyne, Apkarian, and Petek groups. The Petek group will probe the hot electron distribution while the Van Duyne and Apkarian group will observe the chemistry occurring at the hot electron generating site using ultrafast SERS/TERS. The experimental work will be closely coupled to theory performed by the Schatz and Jensen groups. Schatz will examine TERS of hot electron transfer and Jensen will study single molecule charge-transfer events.