Figure 4.
(a) Schematic of the approach employed for probing the hot spot formed in a dimer of Ag nanocubes. The dimer was functionalized with 4-MBT and then exposed to plasma etching to remove the adsorbed 4-MBT molecules. In this case, only the 4-MBT molecules outside the hotspot region (i.e., outside the two touching faces) were removed during the plasma etching. The nanocube dimer was then immersed in a 1,4-BDT solution, resulting in the complete replacement of 4-MBT by 1,4-BDT over its entire surface. (b–d) SERS spectra from a Ag nanocube dimmer functionalized with 4-MBT (top), followed by after plasma etching for 2 min (middle) and then immersion in a 1,4-BDT solution (bottom). The laser was polarized at 0, 45 and 90 degrees with respect to the long axis of the dimer. The scale bars in the insets correspond to 100 nm.
