Near-field Raman Imaging
Near-field Raman imaging is an exceptional microscopy technique which links chemical Raman information to high-resolution Scanning Near-field Optical Microscopy (SNOM). Thus near-field Raman allows for the acquisition of complete high-resolution confocal Raman images. Typically, lateral resolutions of below 100 nm can be achieved.
Through the unique combination of a high-throughput spectroscopic system with the cantilever-based SNOM technique of the WITec Raman-SNOM microscope, an unrivaled sensitivity and imaging quality can be provided by a single microscope setup.
The excitation laser light is focused through the SNOM-tip resulting in a “near-field” (evanescent field) on the far side of the aperture. While the sample is moved on a piezo-driven scan stage, the transmitted light is spectroscopically detected point-by-point and line-by-line in order to generate a hyperspectral Raman image. The optical resolution of the transmitted light is thereby only limited by the diameter of the aperture (< 100 nm). Using a beam deflection setup as in AFM contact mode, it is ensured that the cantilever is always in contact with the sample. In addition the topography can be recorded simultaneously to the measurement.