Fig. 5: Investigating the optical properties of complex Ag nanoframes with varying the number of nanoframes.

a LSPR band profile of 1^st, 2^nd, 3^rd, and 4^th Ag nanoframes, b representative single-particle Raman signals of 1^st, 2^nd, 3^rd, and 4^th Ag nanoframes originating from their corresponding SEM images (scale bar = 200 nm), c plotted data of single-particle Raman intensity (at 1379 cm⁻¹) and theoretically calculated values of electric near-field enhancement as function of the number of nanoframes. Error bars indicate the standard deviations of Raman intensities at 1379 cm⁻¹ of 1^st, 2^nd, 3^rd, and 4^th Ag nanoframes, d charge distribution and e electromagnetic near-field contour maps (in the YZ cross-section) of 1^st, 2^nd, 3^rd, and 4^th Ag nanoframes with different numbers of nanoframes obtained by FEM simulation (Excitation wavelength: 633 nm).