Figure 2

Electron energy loss spectra (a) and energy (b), amplitude (c), and energy-filtered (d,e) maps. (a) Electron energy loss spectra of a 21-nm × 11-nm gold nanoellipsoid linked through DNA strands to a silicon nitride membrane. The inset shows an HAADF image of the nanoparticle. Two representative spectra have been selected and displayed, the first one shown in red (curve i) has a resonant peak at 2.4 eV corresponding to the typical dipolar mode, and the peak of the second one in green (curve ii) is at a lower energy value, 2.15 eV. The two modes can also be identified in the energy map (b) that presents the values of the centers of the fitted Gaussian to the LSPR peak. The amplitude map with the value of the center of the fitted Gaussian to the LSPR peak is shown in (c). The charts in (d) and (e) show the energy-filtered maps centered in the abovementioned modes.