Tip‐Enhanced Long‐Range Dipole–Dipole Interactions With Plasmonic Nanocavities

ABSTRACT Dipole–dipole interactions (DDIs) governing the Förster resonance energy transfer (FRET) are fundamentally constrained by rapid distance decay ( ), limiting nanoscale applications. To overcome this, we introduce a hybrid platform integrating a fixed nanoparticle‐on‐mirror (NPoM) donor cavity with a mobile tip‐enhanced Raman spectroscopy (TERS) tip acceptor. Crucially, the TERS tip functions as an acceptor antenna that amplifies DDI efficiency through nanoscale positioning and tip‐induced plasmonic hotspot engineering. The NPoM cavity provides intense field confinement ( 130), while precise tip positioning (e.g., at nanosphere centers) achieves , enhancing DDI strength by over 10 times compared to standalone cavities. Remarkably, at micrometer‐scale donor–acceptor separations ( ), the TERS tip‐mediated DDI strength surpasses tip‐free systems by 10 times, enabling efficient long‐range energy transfer beyond FRET's classical limits. This hybrid system establishes tunable long‐range DDI unattainable via traditional nanocavity fabrication, enabling high‐sensitivity investigation of micrometer‐range energy transfer and advancing detection of biological molecules at physiological scales.