Infrared optical properties of nanocube dimers with nanometric gaps

Fluorine-doped Indium Oxide (IO) nanocubes separated by nanometric gaps constitute a versatile system hosting high-quality mid-infrared plasmons with potential application in optoelectronics and light harvesting. In this theory-experiment combined work, we predict large tunability of these hybridized plasmon modes by controlling the gap size and the dimensionality of the gap region. We confirm this prediction through Electron Energy-Loss Spectroscopy (EELS) measurements performed in a Scanning Transmission Electron Microscope (STEM). Our theorical-experimental results elucidate the influence of gap geometry on the coupled plasmons and field concentration in doped IO nanostructures, and further suggest exciting applications in plasmonic sensing and surface-enhanced spectroscopies.