Near-field fluorescence imaging by localized field enhancement near a sharp probe tip

This work describes near-field investigations of luminescent nanosamples ba sed on monitoring fluorescence due to the enhanced field around a laser-ill uminated probe tip. These fluorescence effects are investigated as a functi on of probe-sample separation, which identify a strong, spatially localized (approximate to 7 nm) enhancement of the incident laser field in the vicin ity of the probe tip. From a model fit to the fluorescence data, the locali zed enhancement of the electric field is estimated to be > tenfold, which p redicts a significant increase in localized excitation intensity (> 100-fol d) for fluorescence imaging of molecular size samples. (C) 2000 American In stitute of Physics. [S0003-6951(00)04014-6].