Towards the fluorescence resonance energy transfer (FRET) scanning near-field optical microscopy: Investigation of nanolocal FRET processes and FRET probe microscope

The fluorescence resonance energy-transfer (FRET) process is investigated b etween donor dye molecules deposited on the sample surface and acceptor dye molecules deposited on the tips of scanning near-field and atomic force mi croscopes. The FRET process was observed only when the tip acquired contact with the sample and took place in regions of sizes of only a few tens of n anometers with only a few thousands (or even hundreds) of molecules involve d. The dependence of the FRET intensity on the tip-sample acting force is r ecorded and interpreted. In relation to the obtained results, the construct ion of a previously proposed one-atom FRET SNOM is described. (C) 2000 MAIK "Nauka/Interperiodica".