Authors: B. Humbert, J. Grausem, M. Dossot and S. Cremel
Affilation: LCPME UMR 7564 CNRS-UHP, France
Pages: 28 - 31
Keywords: near-field, Raman, luminescence, spectroscopy
Near-field scanning optical microscopy (NSOM or SNOM) offers the opportunity to collect optical information at a spatial scale well below the diffraction limit. Using a silica fiber tip coated with aluminum and having a small aperture (diameter of about 50 nm) at its apex, NSOM opens the fascinating opportunity to access the richness of spectroscopic information at a nano-scale resolution. Indeed, shear-force topography coupled to localized spectral information allow to evidence chemical heterogeneity at sub-micronic spatial scale. This characterization can be crucial to understand surface or interface physico-chemical properties since sub-micronic features can strongly contribute to macroscopic behavior of the samples. This presentation gives two examples of the exploration of reference samples using near-field spectroscopy. The first example concerns the evidence of nano-phases of hydrated copper sulfate on a PbSO4 sample by near-field Raman spectroscopy. A correlation between the tip-sample shear-force interaction and Raman spectra is found and allows to identify the copper sulfate nano-phases. The second example uses near-field luminescence spectroscopy to evidence heterogeneity of the local environment of Europium(III) cations at the surface of a glass sample doped with a small amount of Eu2O3 oxide (1.5 % in weight).