Experimental observation of narrow surface plasmon resonances in gold nanoparticle arrays

We demonstrate that coupling between grating diffraction and localized surface plasmons in two-dimensional gold nanoparticle arrays in water leads to narrow near-infrared resonance peaks in measured far field extinction spectra. Good agreement is obtained between finite difference time domain (FDTD) calculations and experimental extinction spectra. The FDTD calculations predict that the gold nanoparticle arrays exhibit near-field electric field intensity (E(2)) enhancements approximately one order of magnitude greater than those of single isolated gold nanoparticles.