Electricity mediated plasmonic tip engineering on single Ag nanowire for SERS

An electricity-mediated plasmonic engineering was applied on a single Ag nanowire to engineer its tip for surface-enhanced Raman scattering (SERS). Under this constant photoelectric field treatment, a significant sharpening of the tip and reduction of the surface fluctuation was observed for the Ag nanowire tip via in situ atomic force microscopy. A significant SERS signal enhancement was thus obtained after the tip engineering. The relevant dynamic mechanisms of the tip engineering, including the light-induced plasmonic phase transition and electrostatic force driven flow on the Ag nanowire tip are discussed in detail. It is expected that this type of tip engineering will greatly enhance the signal of single metal nanowire SERS probes and provide new insights into fabrication technologies for metal nanostructures.