Rod-Sheath Heterostructures for Plasmonic Focusing

1. Rod-Sheath Heterostructures for Plasmonic Focusing Xiaodong Chen, Shuzou Li, Can Xue, Matthew Banholzer, Chad Mirkin, George Schatz, National Science Foundation DMR-0520513 Over the past year, the Mirkin lab has made progress in two different research avenues. In the first, nanorod smoothing, the lab has developed a two-step method to reduce the roughness of as-prepared Au nanorods to less than 5 nm RMS roughness. The smoothed nanowires exhibit more distinct and resolvable plasmon resonance bands, and plasmonic activity can be tuned. Since many proposed rod-based detection assays depend on identification of plasmon bands, or total plasmonic activity, this could prove a useful result. The group has also successfully made rod-sheath heteronanostructures that demonstrate a plasmonic focusing behavior. While the largest plasmonic intensity is typically found near rod ends in most nanostructures, in these rod-sheath morphologies, it was found find that the investigators can tune the location of the peak electromagnetic activity from the ends to the center of the junction and back to the ends in a periodic manner. Since fine control over plasmonic structure is necessary to push the field of plasmonics forward, this is a very intriguing advance.