(a) Calculated extinction spectra of spherical Au, Ag, and Al nanoparticles with a diameter of 40 nm in a silica matrix. (b) Calculated extinction spectra of spherical Al nanoparticles with diameters of 20, 80, and 140 nm in a silica matrix. (c) Calculated extinction spectra of spherical Au nanoparticles with diameters of 20, 80, and 140 nm in a silica matrix. Calculations are based on Mie’s formulae; for Au, Ag, and Al the optical constants provided in Refs. 6 and 7 were used.
SEM images of Al nanoparticle arrays (a) with an average particle diameter of 40 nm and unit cell dimensions of 90 and 100 nm, respectively; (b) with an average diameter of 138 nm and a period of 280 nm; and (c) with ellipsoidal particles with principle axes of and a period of 200 nm. The particle thickness for all samples is 30 nm.
Experimental and theoretical extinction spectra of the Al nanoparticle array with a diameter of 40 nm, a thickness of 30 nm, and lattice constants of 90 and 100 nm. For FDTD calculations, the optical constants tabulated in Ref. 7 were used.
Comparison of the theoretical extinction spectra of Al nanoparticles with an oblate shape with principle axes of 40 and 30 nm calculated using different models. The solid line (black) denotes FDTD calculations; the dash-dotted (green) line denotes the calculations based on dipolar approximation; the dashed line (red) denotes dipolar approximation calculations with MLWA correction; the dotted line (blue) denotes dipolar approximation with MLWA correction and assuming that the nanoparticle of same total size is coated with 3-nm-thick . The optical constants provided in Ref. 7 were used.
Calculated extinction spectra of Al nanoparticles of 40 nm total diameter and 30 nm total thickness with a 3 nm natural oxide layer using various optical constants. MWLA calculations are based on the optical constants reported in Refs. 7 and 33 (dotted line) and Ref. 34 (dashed line). The solid line curve represents the best fit to the experimental data presented in Fig. 3.
(a) Measured and (b) calculated extinction spectra of Al particle arrays with various diameters as provided in the figure. The array period is 280 nm and the metal thickness is 30 nm. For the FDTD calculations the optical constants listed in Ref. 7 were used.
Measured extinction spectra of ellipsoidal Al nanoparticles of various sizes and aspect ratios. The perpendicular axis with respect to the substrate (film thickness) is 30 nm and the primary axes on the surface plane are provided in the figure. The period of the structures is 200 nm.
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