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Near‐field Raman spectroscopy using a sharp metal tip

Near‐field Raman spectroscopy with a spatial resolution of 20 nm is demonstrated by raster scanning a sharp metal tip over the sample surface. The method is used to image vibrational modes of single‐walled carbon nanotubes. By combining optical and topographical signals rendered by the single‐walled carbon nanotubes, we can separate near‐field and far‐field contributions and quantify the observed Raman enhancement factors.