Subwavelength-size local fluorescent sources based on color centers in LiF for scanning near-field optical microscopy

Local fluorescent probes based on 50–100 nm thick layers of LiF:F2 deposited onto the apex of apertured fiber probe of scanning near-field optical microscope (SNOM) have been prepared and tested. Excellent topographical images with the spatial resolution of a few nanometers and bright near-field optical images with the spatial resolution of about 100 nm (aperture size) were obtained. Experimental evidences of fluorescence resonance energy transfer (FRET) between F2 color centers and a few dyes (rhodamine 700, HITCI, DDI) are presented and perspectives for the use of these probes in FRET SNOM are discussed.