Real-Time Probing Nanopore-in-Nanogap Plasmonic Coupling Effect on Silver Supercrystals with Surface-Enhanced Raman Spectroscopy

Nanopore structures have displayed attractive prospects in diverse important applications such as nanopore‐based biosensors and enhanced spectroscopy. However, on the one hand, the fabrication techniques to obtain sub‐10 nm sized nanopores so far is very limited. On the other hand, the electromagnetic enhancement of nanopores is still relatively low. In this work, using a facile chemical etching strategy on 2D plasmonic Ag nanoparticle supercrystals, fine nanopore arrays with sub‐10 nm pore size have been successfully fabricated and a “nanopore‐in‐nanogap” hybrid plasmon mode has been investigated. An in situ etching and surface‐enhanced Raman spectroscopy (SERS) detection indicate that novel hybrid plasmon structure may create an enhanced electromagnetic coupling and increase SERS signal at ≈10× magnification. The breaking of plasmon bonding dipolar mode and generation of antibonding‐like plasmon mode contribute to this enhanced electromagnetic coupling. The facile etching strategy, as a common approach, may open the doors for the fabrication of nanopores in various compositions for numerous applications.