USE OF A SCANNING NEAR-FIELD OPTICAL MICROSCOPE ARCHITECTURE TO STUDYFLUORESCENCE AND ENERGY-TRANSFER NEAR A METAL

Fluorescence intensity depends strongly on the distance between the em itting molecule and a metallic interface. We show that a scanning near -field optical microscope (SNOM) is a simple and versatile tool for st udying such an effect. The fluorescent molecules are embedded in a lay er upon a silica substrate, and metal is coated on the SNOM tip. We pr esent variations of fluorescence intensity versus tip-sample distance from 800 to similar to 80 nm. A simple model is used to explain the ex perimental results. The proposed setup could be used to study nonradia tive transfer at a nanometric scale. It could also yield to a new type of optical near-field profiler that uses fluorescent signal. (C) 1997 Optical Society of America