Abstract
The optical properties of plasmonic dimers consisting of two adjacent metal nanoparticles can be tuned over a broad spectral range by changing only slightly the dimer geometry. Most drastic are the changes in the smallest interparticles distances, and often only optical spectroscopy together with electromagnetic simulations yields insights into the geometry of the junction. Here, we study the coupling of gold nanoblock dimers, two square nanoantennas with different nanogaps between their closest corners. We identify three different coupling regimescapacitively coupled, conductively bridged, and fused dimersand optically characterize the transitions between them. By combining sample array fabrication, single-particle hyperspectral measurements, and electromagnetic simulations, we were able to examine in detail the effects of junction geometry on the resonance energy and intensity of the plasmon modes supported by gold nanoblock dimers.