MATERIAL CONTRAST IN SCANNING NEAR-FIELD OPTICAL MICROSCOPY AT 1-10 NM RESOLUTION

The tetrahedral tip is used as a light emitting probe for scanning nea r-field optical microscopy (SNOM). It has no aperture as an element fo r the confinement of Light and the techniques of scanning tunneling mi croscopy and SNOM can be combined with the same probing tip. Silver gr ains are distinguished from gold grains by their specific near-field o ptical contrast in SNOM transmission mode images of mixed films of sil ver and gold at a lateral resolution in the nanometer range and an edg e resolution of 1 nm for selected grains. The contrast is explained in terms of a quasielectrostatic model of a local light-emitting source interacting with the object.