Effect of Intertip Coupling on the Plasmonic Behavior of Individual Multitipped Gold Nanoflower

We report here, the first experimental realization on the selective excitation of two closely lying tips from the same spherical core of a multitipped gold nanoparticle with flower-like morphology. This gives strong multipeaked resonance in the near-infrared region of the far-field emission spectra showing a clear signature of tip to tip coupling. The cathodoluminescence (CL) technique in a scanning electron microscope (SEM) combined with finite-difference time-domain (FDTD) simulation has helped us to identify the coupled plasmon modes to be originated from the interaction between two closely spaced tips with a narrow angular separation. Our analysis further estimates a range of angular separation between the tips that triggers the onset of the intertip coupling.