Polymer-encapsulated silver nanoparticle monomer and dimer for surface-enhanced Raman scattering

Polarization-dependent surface-enhanced Raman scattering (SERS) from individual polymer-encapsulated monomer and dimer of Ag nanoparticles (NPs) was examined. The different SERS behavior between the monomer and the dimer were elucidated in terms of electromagnetic (EM) simulations by finite element method while the dimer plasmon resonance contributes to the strong SERS effect of the NP dimer. Our results also demonstrate that the encapsulated polymer layer provides favorable protection to the concerned NPs and the adsorbates without introducing background signals.