Abstract
The discovery of single-molecule sensitivity via surfaceenhanced
Raman scattering on resonantly excited noble metal nanoparticles
has brought an increasing interest in its applications to the molecule
detection and identification. Periodic gold bowtie nanostructures have
recently been shown to give a large enhancement factor sufficient for single
molecule detection. In this work, we simulate the plasmon resonance for
periodic gold bowtie nanostructures. The difference between the dipole and
the quadrupole resonances is described by examining the magnitude and
phase of electric field, the bound surface charge, and the polarization. The
gap size dependence of the field enhancement can be interpreted by
considering cavity field enhancement. Also, additional enhancement is
obtained through the long-range collective photonic effect when the bowtie
array periodicity matches the resonance wavelength.
