Fig. 1
Calculated extinction and absorption efficiencies with and without consideration of surface scattering of conduction electrons, where Qext (Ext) stands for extinction efficiency (normalized extinction) and Qabs (Abs) stands for absorption efficiency (normalized absorption). The scattering efficiency (normalized scattering) is the difference between the Qext (Ext) and Qabs (Abs). All calculations are carried out by Mie theory, with silica and surrounding medium’s indices assumed to be 1.45 and 1.5 respectively. Gold’s dielectric constants without surface scattering are from reference [38], while those with surface scattering are given by Eqs. (1)~(3). a and b are for (80-nm-diameter silica core)@(15-nm-thick gold shell). c and d are for (80-nm-diameter silica core)@(25-nm-thick gold shell). e and f are for (80-nm-diameter silica core)@(35-nm-thick gold shell). g and h are for (80-nm-diameter silica core)@(45-nm-thick gold shell). The left column, i.e., a, c, e, and g, is the corresponding efficiencies as calculated by Mie theory. The right column, i.e., b, d, and f, is the efficiencies normalized to the dipolar resonance peak (the resonance peak between 700 and 800 nm), and h the efficiencies normalized to the quadrupolar resonance peak (the peak between 550 and 600 nm)