Local fluorescent probes for the fluorescence resonance energy transfer scanning near-field optical microscopy

Author :G. T. Shubeita, S. K. Sekatskii, G. Dietler, V.S. Letokhov
Publication :Applied Physics Letters
Volume :80
Number :15
Pages :2625-2627
Year :2002

We present fluorescence resonance energy transfer ~FRET! images of donor dye molecule clusters
recorded using a local fluorescence probe for scanning near-field optical microscopy ~SNOM!:
standard apertured SNOM fiber tip coated with the 30’100-nm-thick polymer layer stained with the
acceptor dye molecules. The tip works as a ”self-sharpening pencil”: the apical layers of the
FRET-active tip coating are mechanically worn out during scanning thus continuously exposing a
fresh active apex to continue imaging. Only a few tens of acceptor molecules are used to form the
optical images, and using such an approach spatial resolution better than the size of the aperture is