Near-field Raman spectroscopy

An optical device was constructed to collect near-field Raman spectra (NFRS ) and far-field scattering Raman spectra simultaneously on the same sample area. In Raman applications where the studied samples do not enjoy any adva ntages of resonance effects, the nanoprobe may be used only as a nanodetect or in order to avoid damage of the tip by the necessary laser powers. The s ilicon-based samples, which are either calibrated grid or a single crystal, were studied by NFRS and conventional scattering Raman spectroscopy, The n ear-field Raman signal of silicon is divided by at least four when the tip- silicon substrate distance is separated by a 100 nm layer of oxide. Moreove r, between the NFR spectrum and the far-field spectrum, on the single cryst al, a shift of about 10 cm(-1) is displayed. Some interpretations are discu ssed. These experiments confirm the potential of the NFRS already emphasize d previously in the literature. Copyright (C) 1999 John Wiley & Sons, Ltd.