Simple and versatile route to high yield face-to-face dimeric assembly of Ag nanocubes and their surface plasmonic properties.

We have demonstrated the higher yield dimerization of single-crystalline Ag nanocubes through preciously controlled face-selective functionalization. With the achievement of the higher yield dimerization, we could thus observe some interesting optical properties of the dimer. Both experimental and theoretical studies revealed that the 50-nm-diameter Ag nanocubes dimers with a ca. 3.3 nm gap at their junction exhibited two plasmon peaks centered at 446 nm and 600 nm, which contributed to transverse and longitudinal plasmon resonances, respectively. Elctromagnetic calculations based on the FDTD method clearly showed that a greater enhancement of the local field occurred, with an average amplitude of the electric field of 22, at the fractal space between the aggregated Ag nanocubes when the dimer was illuminated under longitudinally polarized light.