Figure 3

Magnitude of F, the on-axis electric field enhancement factor, for a prolate Ag spheroid with semiaxes a = 10 nm and c = 40 nm. a Dependence of |F| on position z; the point z = 40 nm is at the spheroid’s sharp tip. Solid line gives the exact result of Eq. 8; boxes and circles give the results of DDA-based simulations with N = 24679 subunits employing LEC and CM polarizabilities, respectively. b Dependence of |F| at z = 41 nm on the edge length d of the DDA subunits. The dotted line at |F| = 102.7 gives the exact result of Eq. 8; boxes and circles give the results of DDA-based simulations employing LEC and CM polarizabilities, respectively