Effective plasmon coupling in conical cavities for sensitive surface enhanced Raman scattering with quantitative...

Area of Science:

• Nanotechnology
• Plasmonics
• Spectroscopy

Background:

• Surface-enhanced Raman scattering (SERS) is a powerful technique for molecular detection.
• Developing highly sensitive and reproducible SERS substrates is crucial for chemical and biomedical applications.
• Nanocavity arrays offer unique optical properties for enhancing SERS signals.

Purpose of the Study:

• To fabricate and characterize conical silver nanocavity arrays for SERS applications.
• To investigate the influence of cavity structure on SERS activity.
• To evaluate the potential of these arrays for quantitative chemical and biomedical analysis.

Main Methods:

• Fabrication of conical silver nanocavity arrays using porous alumina templates.
• Controlled deposition of silver (Ag) to create complete and cracked cavity structures.
• Surface-enhanced Raman scattering (SERS) measurements and numerical simulations.

Main Results:

• Cracked silver nanocavity arrays exhibit significantly higher SERS activity compared to complete ones.
• Numerical simulations confirm enhanced local electric fields due to coupled cavity modes and silver nanoparticles (NPs).
• Optimized arrays achieve an enhancement factor (EF) of ~7.4 × 10^6 with excellent uniformity (RSD ~5%) for rhodamine 6G (R6G).

Conclusions:

• Cracked silver nanocavity arrays are superior SERS substrates due to nanoparticle-induced field enhancement.
• These arrays demonstrate high sensitivity, reproducibility, and quantitative analysis capabilities.
• The developed nanocavity arrays hold great potential for advanced chemical and biomedical sensing.