A PRACTICAL NANOSCOPIC RAMAN IMAGING TECHNIQUE REALIZED BY NEAR-FIELD ENHANCEMENT

TL;DRAbstract

Abstract. Near-field scanning optical microscope (NSOM) has the potential to become a very important tool for material characterization due to its ability to investigate the structure and micro-environment of materials in nano-scale by performing spectroscopy as well as topographic mapping. However, near-field Raman results have been rarely reported although Raman spectra are unique in chemical and structural identification. This is due to the fact that Raman signal is intrinsically weak (less than 1 in 107 photons) and the laser power emerging from tip is extremely low (typically 100 nW) because of the low optical throughput of metal coated fiber tips. The long integration time (typically 10 minutes per spectrum) required for collecting good quality Raman spectra makes it impractical to construct a Raman image through this conventional method. In this paper, we report an integration of NSOM and Raman spectrometer using an apertureless configuration, in which the laser is focused onto

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