Figure 1.
(A) SEM and TEM (inset) images of Au nanocages synthesized using the galvanic replacement reaction in which Ag nanocubes serve as a sacrificial template. The scale bar in the inset represents 100 nm. (B) The absorption (Cabs), scattering (Csca), and extinction (Cext) cross sections (note that Cext = Cabs + Csca) as a function of wavelength were calculated using the DDA method for a Au nanocage with the following geometrical parameters: edge length = 65 nm, wall thickness = 7.5 nm, and corner holes with diameter = 20 nm. Also for the DDA calculations, the nanocages were assumed to be in water and have a composition of 37% Ag and 63% Au. The inset shows the UV–visible absorbance spectrum for the nanocages shown in (A), which have a resonance peak at 800 nm, in agreement with the calculations.