Scanning plasmon near-field microscope

A new optical near-field microscope with a lateral resolution of 3 nm (λ/200) is presented. Resonantly excited extended surface plasmons generate an optical near field which is locally probed by a sharp tip. The interaction of the surface plasmons with the tip can be understood in terms of elastic plasmon scattering and radiationless energy transfer from the tip to the sample. The new technique may permit the detection and spectrscopic identification of single adsorbed molecules.