Theoretical studies on the near field properties of non-concentric core-shell nanoparticle dimers

The concentric core-shell nanoparticle dimers have hot spots with enhanced electric fields in their junctions, which can be used in the surface enhanced Raman spectra analysis. Here the non-concentric core-shell nanoparticle dimers are proposed by introducing a shift between the dielectric core and the metal shell By using the three dimensional finite difference time domain method, the plasmon resonances and the near field properties of the core-shell nanoparticle dimers affected by the non-concentric shift, dimer separation, excitation wavelength and polarization are analyzed in detail The results show that the local near fields of the non-concentric core-shell nanoparticle dimers can be much more enhanced than those of the concentric ones. Also the plasmon resonance wavelengths of the dimers can be effectively tuned by the non-concentric shifts between the core and shell. The proposed nanostructures can have great potential in various near field applications (C) 2010 Elsevier B V All rights reserved