Photonic nanopatterns of gold nanostructures indicate the excitation of surface plasmon modes of a wavelength of 50–100 nm by scanning near-field optical microscopy

Scanning near‐field optical microscopy images of metal nanostructures taken with the tetrahedral tip (T‐tip) show a distribution of dark and bright spots at distances in the order of 25–50 nm. The images are interpreted as photonic nanopatterns defined as calculated scanning near‐field optical microscopy images using a dipole serving as a light‐emitting scanning near‐field optical microscopy probe. Changing from a positive to a negative value of the dielectric function of a sample leads to the partition of one spot into several spots in the photonic nanopatterns, indicating the excitation of surface plasmons of a wavelength in the order of 50–100 nm in metal nanostructures.