Tunable plasmon resonances in a metallic nanotip-film system.
Tip-enhanced Raman spectroscopy (TERS) has emerged as a powerful tool for optical imaging at nanoscale spatial resolution, and for investigating the vibrational properties of molecules adsorbed on a substrate. Plasmonic enhancement of the electromagnetic fields near a metallic nanostructure plays a very important role in TERS, where resonant excitation of plasmons is crucial. When two metallic nanostructures are placed at a gap of nanometric distance, their plasmons can interact with one other and result in hybridized shifted plasmon modes. Here, we apply this idea to TERS and demonstrate a significant tunability of the plasmon resonance enabling large electric field enhancement at a desired excitation wavelength. This finding paves the way for efficient optimization of TERS in imaging and spectroscopy applications.
Department of Applied Physics, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan.
Kazumasa
K
Uetsuki
Prabhat
P
Verma
Peter
P
Nordlander
Satoshi
S
Kawata