Imaging spatial plasmon mode of nanocavity formed by Au tip and Au nanorod lattice in tip-enhanced Raman spectroscopy

The integration of Au nanorods in tip-enhanced Raman spectroscopy (TERS) presents a significant increase in the enhancement factor, primarily due to the gap-mode effect. By aligning Au nanorods in parallel, we construct an Au nanorod lattice, referred to as the Au nanolattice, which further amplifies the advantages of TERS imaging due to the induced inter-nanorod surface plasmon resonance. A critical aspect in this research involves investigating the distribution of hotspots within the nanolattice during TERS measurements. Additionally, we demonstrate that the tip-lattice nanocavity is a predominant factor in determining both the intensity and spatial distribution of these hotspots. Employing the experimental and simulation results, we illustrate the enhancement effect of the tip-lattice cavity and elucidate the connection between the hotspot intensity and cavity size. This comprehensive approach contributes to our understanding of the nano-lattice's role in TERS and offers valuable insights for optimizing nanophotonic applications.