文摘
An ensemble of hemiellipsoidally shaped silver nanoislands was grown on a soda-lime glass substrate using the combination of ion exchange, thermal poling, and out-diffusion techniques. The nanoislands were characterized using scanning electron and atomic force microscopy, and their dipole and quadrupole plasmonic properties were studied using dark-field spectroscopy and numerical modeling using discrete dipole approximation and finite element analysis. Numerically simulated scattering spectra demonstrate good correspondence with the single-particle dark-field measurements. The maps of the dipole surface plasmon resonance (SPR) wavelength and intensity are plotted in nanoisland height-diameter coordinates. It is shown that SPR shifts to the red spectral region with the increase of nanoisland width and with the decrease in the nanoisland base diameter. The quadrupole resonance observed at shorter wavelengths demonstrates higher Q-factor, and stronger enhancement and localization in the near-field.