Synthesis and utilization of LaVO4:Eu3+ nanoparticles as fluorescent near-field optical sensors.

We report the use of fluorescent La1-xEuxVO4 (0.1 ≤ x ≤ 0.3) nanoparticles as near-field optical sensors. A single particle was glued at the end of a sharp atomic force microscope tip and scanned on the surface of a test sample made of sub-micron sized holes in a thin silver film. Illumination of the sample was performed at λ = 532 nm in a transmission configuration. The light transmitted through the apertures induced the fluorescence of europium ions. The collection of the fluorescence light as a function of the tip position above the surface allowed to map the near-field distribution in the vicinity of the holes, at different heights above the surface showing the beam divergence in free space above the sample. (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]