Figure 1

(a) Extinction spectrum for a silica core-gold shell nanoparticle (diameter $d=100$ nm; shell thickness $t=20$ nm) in water ($n=1.33$) calculated using Mie theory and the dielectric constant of gold published in Ref. 35. The extinction cross section for the first two surface plasmon resonance modes is also shown, namely, the dipolar ($l=1$) and the quadrupolar ($l=2$) modes. (b) Extinction spectra for a 100 nm diameter gold solid sphere and 100 nm diameter silica core-gold shell nanoparticles in water ($n=1.33$) calculated for different shell thicknesses ($t=6$, 10, and 20 nm).Reuse & Permissions

Figure 2

(a) SH scattering cross section for a silica core-gold shell nanoparticle (diameter $d=100$ nm; shell thickness $t=20$ nm) in water ($n$ $=$ 1.33) calculated with the extended Mie theory using the dielectric constant of gold published in Ref. 35. The contributions of the first two SH emission modes are shown, namely, the dipolar (red curve) and quadrupolar modes (blue curve). The labeled resonances correspond to those discussed in the main text. (b) SH scattering cross section for a 100 nm diameter gold solid sphere and 100 nm diameter silica core-gold shell nanoparticles in water ($n$ $=$ 1.33) calculated for different shell thicknesses ($t=6$, 10, and 20 nm). The arrows indicate the wavelength shift of the different resonances when the shell thickness decreases.Reuse & Permissions

Figure 3

Calculated fundamental wavelength ${\lambda }_{\max }$ of the maximum of the SH (a) dipolar and (b) quadrupolar emission modes for a silica core-gold shell nanoparticle in water as a function of the shell thickness $t$ for four nanoshell diameters. Solid lines correspond to fits with exponential functions.Reuse & Permissions

Figure 4

Fractional shift Δλ/${\lambda }_0$ of the SH (a) dipolar and (b) quadrupolar emission modes for a silica core-gold shell nanoparticle in water with respect to that of a solid gold nanosphere with the same size, as a function of the ratio of the shell thickness to the core radius $t$/$R$ for four different diameters. The solid lines correspond to fits with exponential functions.Reuse & Permissions