Blue-Shifted Narrow Localized Surface Plasmon Resonance from Dipole Coupling in Gold Nanoparticle Random Arrays

In this work, we develop a simple method to produce highly uniform localized surface plasmon resonance (LSPR) substrates based on self-assembly of colloidal gold nanoparticles onto pretreated glass substrates. The LSPR wavelength of the gold nanoparticle arrays is blue-shifted from that of the gold nanoparticles in solution and the single gold nanoparticles on glass substrate. The LSPR width is narrower than that of the single gold nanoparticles. The blue-shifted LSPR is due to the long-range dipole coupling in the gold nanoparticle random arrays indicated from simulations using the T-matrix method. In addition to the popularly used LSPR wavelength dependence on the dielectric environment, we have found that the LSPR width of the gold nanoparticle random arrays is also sensitive to the change in the dielectric environment. The LSPR substrates are reproducible, uniform, and robust with potential applications in LSPR sensing and imaging