Au nanodiscs which are resonant in the visible spectral regime exhibit a dipolar oscillation mode when imaged at a wavelength of 633nm. The amplitude image of an approx. 90nm diameter Au disk (height 20nm) exhibits two bright lobes at the rim of the disk, which are oscillating 180° out of phase. Note, in order not to disturb the field of the disk, a probing tip made of a weak dielectric has to be used for near-field imaging. For the recorded images a carbon nanotube tip was used.

Application-Mapping-optical-fields-of-resonant-particles