Figure 7.

(a) line scan of topography indicating feature size of 94 nm (b) line scan of normalized optical force (from experiment in red color) with spherical gold nanoparticle in the longitudinal incident field indicating feature size of 71 nm and compared with the line scans of normalized optical force (in blue color) and normalized |E_z|² of only nanoparticle (in green color) from numerical calculations (c) Model used in numerical calculations with elliptical gold nanoparticle scanning over the spherical gold nanoparticle and following the theoretical AFM topography curve (d) line scan of normalized optical force (from experiment in red color) with spherical gold nanoparticle in the transverse incident field and compared with the line scans of normalized optical force (in blue color) and normalized |E_ρ|² of only nanoparticle (in green color) from numerical calculations. Insets in Fig. 7 (b) and (d) show the zoomed-in images of the measured optical force distributions on the nanoparticles.